diff --git a/composer.json b/composer.json
index f12abd3f7d0..cf3cec1b3df 100644
--- a/composer.json
+++ b/composer.json
@@ -50,11 +50,10 @@
 	},
 	"autoload-dev": {
 		"classmap": [
-			"config/",
-			"tests/WP"
+			"config/"
 		],
 		"psr-4": {
-			"Yoast\\WP\\SEO\\Tests\\Unit\\": "tests/Unit/"
+			"Yoast\\WP\\SEO\\Tests\\": "tests/"
 		}
 	},
 	"config": {
@@ -84,7 +83,7 @@
 			"Yoast\\WP\\SEO\\Composer\\Actions::check_coding_standards"
 		],
 		"check-cs-thresholds": [
-			"@putenv YOASTCS_THRESHOLD_ERRORS=129",
+			"@putenv YOASTCS_THRESHOLD_ERRORS=127",
 			"@putenv YOASTCS_THRESHOLD_WARNINGS=202",
 			"Yoast\\WP\\SEO\\Composer\\Actions::check_cs_thresholds"
 		],
diff --git a/phpcs.xml.dist b/phpcs.xml.dist
index 4b240fb9d5d..566a6392e4a 100644
--- a/phpcs.xml.dist
+++ b/phpcs.xml.dist
@@ -242,7 +242,7 @@
 
 	<!-- The unit tests are not run within the context of a WP install, so overwritting globals is fine. -->
 	<rule ref="WordPress.WP.GlobalVariablesOverride">
-		<exclude-pattern>/tests/Unit/*</exclude-pattern>
+		<exclude-pattern>/tests/*</exclude-pattern>
 	</rule>
 
 	<!-- Allow for the double/mock classes to override methods just to change the visibility. -->
@@ -283,7 +283,7 @@
 		<include-pattern>/config/*\.php$</include-pattern>
 		<include-pattern>/lib/*\.php$</include-pattern>
 		<include-pattern>/src/*\.php$</include-pattern>
-		<include-pattern>/tests/Unit/*\.php$</include-pattern>
+		<include-pattern>/tests/*\.php$</include-pattern>
 	</rule>
 
 	<!-- Only enable the prefix all globals rules for the "new" code for now.
@@ -295,7 +295,7 @@
 		<include-pattern>*/config/*\.php$</include-pattern>
 		<include-pattern>*/lib/*\.php$</include-pattern>
 		<include-pattern>*/src/*\.php$</include-pattern>
-		<include-pattern>*/tests/Unit/*\.php$</include-pattern>
+		<include-pattern>*/tests/*\.php$</include-pattern>
 
 		<!-- Exclude hooks everywhere for the time being until the prefixes will be fixed. -->
 		<exclude name="WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound"/>
@@ -303,13 +303,13 @@
 
 	<!-- The below issues will be fixed in YoastCS 3.0, after which these excludes can be removed. -->
 	<rule ref="Yoast.Files.FileName.InvalidClassFileName">
-		<exclude-pattern>/tests/Unit/*\.php$</exclude-pattern>
+		<exclude-pattern>/tests/*\.php$</exclude-pattern>
 	</rule>
 	<rule ref="Yoast.Files.FileName.InvalidTraitFileName">
 		<exclude-pattern>/tests/Unit/*\.php$</exclude-pattern>
 	</rule>
 	<rule ref="Yoast.NamingConventions.NamespaceName.Invalid">
-		<exclude-pattern>/tests/Unit/*_*/*\.php$</exclude-pattern>
+		<exclude-pattern>/tests/(Unit|WP)/*_*/*\.php$</exclude-pattern>
 	</rule>
 	<rule ref="Yoast.Commenting.FileComment.Unnecessary">
 		<exclude-pattern>/tests/*/bootstrap\.php$</exclude-pattern>
diff --git a/phpunit-wp.xml.dist b/phpunit-wp.xml.dist
index 37e440c9639..a155bbefe75 100644
--- a/phpunit-wp.xml.dist
+++ b/phpunit-wp.xml.dist
@@ -20,7 +20,7 @@
 	>
 	<testsuites>
 		<testsuite name="yoastseo">
-			<directory prefix="test-" suffix=".php">./tests/WP</directory>
+			<directory suffix="Test.php">./tests/WP</directory>
 		</testsuite>
 	</testsuites>
 
diff --git a/tests/WP/Admin/test-class-admin-asset-dev-server-location.php b/tests/WP/Admin/Asset_Dev_Server_Location_Test.php
similarity index 87%
rename from tests/WP/Admin/test-class-admin-asset-dev-server-location.php
rename to tests/WP/Admin/Asset_Dev_Server_Location_Test.php
index 47d12fac6ff..1892d6fca08 100644
--- a/tests/WP/Admin/test-class-admin-asset-dev-server-location.php
+++ b/tests/WP/Admin/Asset_Dev_Server_Location_Test.php
@@ -1,16 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin;
+
+use WPSEO_Admin_Asset;
+use WPSEO_Admin_Asset_Dev_Server_Location;
 use Yoast\WPTestUtils\WPIntegration\TestCase;
 
 /**
  * Tests WPSEO_Admin_Asset_Dev_Server_Location.
  */
-final class Admin_Asset_Dev_Server_Location_Test extends TestCase {
+final class Asset_Dev_Server_Location_Test extends TestCase {
 
 	/**
 	 * Default arguments to use for creating a new Admin_Asset.
diff --git a/tests/WP/test-class-admin-asset-manager.php b/tests/WP/Admin/Asset_Manager_Test.php
similarity index 89%
rename from tests/WP/test-class-admin-asset-manager.php
rename to tests/WP/Admin/Asset_Manager_Test.php
index 91d4126e038..12332ca0369 100644
--- a/tests/WP/test-class-admin-asset-manager.php
+++ b/tests/WP/Admin/Asset_Manager_Test.php
@@ -1,16 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin;
+
+use WPSEO_Admin_Asset;
+use WPSEO_Admin_Asset_Manager;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Admin_Asset_Manager_Test extends TestCase {
+class Asset_Manager_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
@@ -36,7 +35,7 @@ public function set_up() {
 	 */
 	public function test_DEFAULT_register() {
 		$instance = $this
-			->getMockBuilder( 'WPSEO_Admin_Asset_Manager' )
+			->getMockBuilder( WPSEO_Admin_Asset_Manager::class )
 			->setMethods(
 				[
 					'register_scripts',
@@ -88,7 +87,7 @@ public function test_enqueue_script() {
 		$class_instance->register_assets();
 
 		$class_instance->enqueue_script( 'post-edit' );
-		$this->assertTrue( wp_script_is( WPSEO_Admin_Asset_Manager::PREFIX . 'post-edit', 'enqueued' ) );
+		$this->assertTrue( \wp_script_is( WPSEO_Admin_Asset_Manager::PREFIX . 'post-edit', 'enqueued' ) );
 	}
 
 	/**
@@ -101,7 +100,7 @@ public function test_enqueue_style() {
 		$class_instance->register_assets();
 
 		$class_instance->enqueue_style( 'metabox-css' );
-		$this->assertTrue( wp_style_is( WPSEO_Admin_Asset_Manager::PREFIX . 'metabox-css', 'enqueued' ) );
+		$this->assertTrue( \wp_style_is( WPSEO_Admin_Asset_Manager::PREFIX . 'metabox-css', 'enqueued' ) );
 	}
 
 	/**
@@ -114,7 +113,7 @@ public function test_wrong_enqueue_style() {
 		$class_instance->register_assets();
 
 		$class_instance->enqueue_style( 'nonexisting' );
-		$this->assertFalse( wp_style_is( WPSEO_Admin_Asset_Manager::PREFIX . 'nonexisting', 'enqueued' ) );
+		$this->assertFalse( \wp_style_is( WPSEO_Admin_Asset_Manager::PREFIX . 'nonexisting', 'enqueued' ) );
 	}
 
 	/**
@@ -141,7 +140,7 @@ public function test_register_script() {
 		$result = $wp_scripts->registered[ WPSEO_Admin_Asset_Manager::PREFIX . 'handle' ];
 
 		$this->assertEquals( WPSEO_Admin_Asset_Manager::PREFIX . 'handle', $result->handle );
-		$this->assertEquals( 'http://' . WP_TESTS_DOMAIN . '/wp-content/plugins/wordpress-seo/js/dist/src.js', $result->src );
+		$this->assertEquals( 'http://' . \WP_TESTS_DOMAIN . '/wp-content/plugins/wordpress-seo/js/dist/src.js', $result->src );
 		$this->assertEquals( [ 'deps' ], $result->deps );
 		$this->assertEquals( 'version', $result->ver );
 		$this->assertEquals( [ 'group' => 1 ], $result->extra );
@@ -193,7 +192,7 @@ public function test_register_style() {
 		$result = $wp_styles->registered[ WPSEO_Admin_Asset_Manager::PREFIX . 'handle' ];
 
 		$this->assertEquals( WPSEO_Admin_Asset_Manager::PREFIX . 'handle', $result->handle );
-		$this->assertEquals( 'http://' . WP_TESTS_DOMAIN . '/wp-content/plugins/wordpress-seo/css/dist/src.css', $result->src );
+		$this->assertEquals( 'http://' . \WP_TESTS_DOMAIN . '/wp-content/plugins/wordpress-seo/css/dist/src.css', $result->src );
 		$this->assertEquals( [ 'deps' ], $result->deps );
 		$this->assertEquals( 'version', $result->ver );
 		$this->assertEquals( 'print', $result->args );
@@ -241,7 +240,7 @@ public function test_register_scripts() {
 			],
 		];
 
-		$class_instance = $this->getMockBuilder( 'WPSEO_Admin_Asset_Manager' )
+		$class_instance = $this->getMockBuilder( WPSEO_Admin_Asset_Manager::class )
 			->setMethods( [ 'register_script' ] )
 			->getMock();
 
@@ -276,7 +275,7 @@ public function test_register_styles() {
 			],
 		];
 
-		$class_instance = $this->getMockBuilder( 'WPSEO_Admin_Asset_Manager' )
+		$class_instance = $this->getMockBuilder( WPSEO_Admin_Asset_Manager::class )
 			->setMethods( [ 'register_style' ] )
 			->getMock();
 
@@ -298,7 +297,7 @@ public function test_register_styles() {
 	 */
 	public function test_register_assets() {
 
-		$class_instance = $this->getMockBuilder( 'WPSEO_Admin_Asset_Manager' )
+		$class_instance = $this->getMockBuilder( WPSEO_Admin_Asset_Manager::class )
 			->setMethods( [ 'register_scripts', 'register_styles' ] )
 			->getMock();
 
diff --git a/tests/WP/Admin/test-class-admin-asset-seo-location.php b/tests/WP/Admin/Asset_SEO_Location_Test.php
similarity index 66%
rename from tests/WP/Admin/test-class-admin-asset-seo-location.php
rename to tests/WP/Admin/Asset_SEO_Location_Test.php
index c261a0aea4b..421110efd18 100644
--- a/tests/WP/Admin/test-class-admin-asset-seo-location.php
+++ b/tests/WP/Admin/Asset_SEO_Location_Test.php
@@ -1,16 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin;
+
+use WPSEO_Admin_Asset;
+use WPSEO_Admin_Asset_SEO_Location;
 use Yoast\WPTestUtils\WPIntegration\TestCase;
 
 /**
- * Tests WPSEO_Admin_Asset.
+ * Tests WPSEO_Admin_Asset_SEO_Location.
  */
-final class WPSEO_Admin_Asset_SEO_Location_Test extends TestCase {
+final class Asset_SEO_Location_Test extends TestCase {
 
 	/**
 	 * Tests the get_url function.
@@ -29,11 +28,11 @@ public function test_get_url() {
 		];
 		$asset      = new WPSEO_Admin_Asset( $asset_args );
 
-		$expected_js    = home_url() . '/wp-content/plugins/wordpress-seo/js/dist/src.js';
-		$expected_css   = home_url() . '/wp-content/plugins/wordpress-seo/css/dist/src.css';
+		$expected_js    = \home_url() . '/wp-content/plugins/wordpress-seo/js/dist/src.js';
+		$expected_css   = \home_url() . '/wp-content/plugins/wordpress-seo/css/dist/src.css';
 		$expected_empty = '';
 
-		$location = new WPSEO_Admin_Asset_SEO_Location( WPSEO_FILE );
+		$location = new WPSEO_Admin_Asset_SEO_Location( \WPSEO_FILE );
 
 		$actual_js    = $location->get_url( $asset, WPSEO_Admin_Asset::TYPE_JS );
 		$actual_css   = $location->get_url( $asset, WPSEO_Admin_Asset::TYPE_CSS );
diff --git a/tests/WP/test-class-admin-asset.php b/tests/WP/Admin/Asset_Test.php
similarity index 95%
rename from tests/WP/test-class-admin-asset.php
rename to tests/WP/Admin/Asset_Test.php
index c2950821206..1b340445287 100644
--- a/tests/WP/test-class-admin-asset.php
+++ b/tests/WP/Admin/Asset_Test.php
@@ -1,16 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin;
+
+use InvalidArgumentException;
+use WPSEO_Admin_Asset;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Admin_Asset_Test extends TestCase {
+class Asset_Test extends TestCase {
 
 	/**
 	 * Tests the constructor when no name and src are passed.
diff --git a/tests/WP/Admin/test-class-database-proxy.php b/tests/WP/Admin/Database_Proxy_Test.php
similarity index 96%
rename from tests/WP/Admin/test-class-database-proxy.php
rename to tests/WP/Admin/Database_Proxy_Test.php
index 1098d66f9ad..a02b00e0260 100644
--- a/tests/WP/Admin/test-class-database-proxy.php
+++ b/tests/WP/Admin/Database_Proxy_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin;
+
+use WPSEO_Database_Proxy;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Database_Proxy_Test extends TestCase {
+class Database_Proxy_Test extends TestCase {
 
 	/**
 	 * Table name for use by the DB Proxy.
@@ -434,7 +432,7 @@ public function test_register_table() {
 
 		$proxy_table_name = self::$proxy_table_name . '_duplicate';
 
-		$this->assertTrue( in_array( $proxy_table_name, $wpdb->tables, true ) );
+		$this->assertTrue( \in_array( $proxy_table_name, $wpdb->tables, true ) );
 	}
 
 	/**
@@ -447,6 +445,6 @@ public function test_register_table_global() {
 
 		$proxy_table_name = self::$proxy_table_name . '_duplicate';
 
-		$this->assertTrue( in_array( $proxy_table_name, $wpdb->ms_global_tables, true ) );
+		$this->assertTrue( \in_array( $proxy_table_name, $wpdb->ms_global_tables, true ) );
 	}
 }
diff --git a/tests/WP/Admin/test-class-admin-editor-specific-replace-vars.php b/tests/WP/Admin/Editor_Specific_Replace_Vars_Test.php
similarity index 95%
rename from tests/WP/Admin/test-class-admin-editor-specific-replace-vars.php
rename to tests/WP/Admin/Editor_Specific_Replace_Vars_Test.php
index 010bd1336fc..1e60d05338b 100644
--- a/tests/WP/Admin/test-class-admin-editor-specific-replace-vars.php
+++ b/tests/WP/Admin/Editor_Specific_Replace_Vars_Test.php
@@ -1,17 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin;
+
+use WPSEO_Admin_Editor_Specific_Replace_Vars;
 use Yoast\WP\SEO\Tests\WP\Doubles\Admin\Editor_Specific_Replace_Vars_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Admin_Editor_Specific_Replace_Vars_Test extends TestCase {
+class Editor_Specific_Replace_Vars_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
@@ -241,7 +239,7 @@ public function test_determine_for_archive_with_a_custom_fallback() {
 	 */
 	public function test_determine_for_archive_with_a_existing_archive() {
 		$class_instance = $this
-			->getMockBuilder( 'WPSEO_Admin_Editor_Specific_Replace_Vars' )
+			->getMockBuilder( WPSEO_Admin_Editor_Specific_Replace_Vars::class )
 			->setMethods( [ 'has_for_page_type' ] )
 			->getMock();
 
@@ -294,7 +292,7 @@ private function create_and_get_with_post_type( $post_type = 'post' ) {
 	 * @covers WPSEO_Admin_Editor_Specific_Replace_Vars::get
 	 */
 	public function test_editor_specific_replacement_variables_filter() {
-		add_filter( 'wpseo_editor_specific_replace_vars', [ $this, 'filter_editor_specific_replacement_variables' ] );
+		\add_filter( 'wpseo_editor_specific_replace_vars', [ $this, 'filter_editor_specific_replacement_variables' ] );
 
 		$expected_replacement_variables = [
 			'page'                     => [ 'pt_single', 'pt_plural', 'parent_title' ],
@@ -313,7 +311,7 @@ public function test_editor_specific_replacement_variables_filter() {
 			$this->class_instance->get()
 		);
 
-		remove_filter( 'wpseo_editor_specific_replace_vars', [ $this, 'filter_editor_specific_replacement_variables' ] );
+		\remove_filter( 'wpseo_editor_specific_replace_vars', [ $this, 'filter_editor_specific_replacement_variables' ] );
 	}
 
 	/**
@@ -322,7 +320,7 @@ public function test_editor_specific_replacement_variables_filter() {
 	 * @covers WPSEO_Admin_Editor_Specific_Replace_Vars::get
 	 */
 	public function test_editor_specific_replacement_variables_filter_with_wrong_return_value() {
-		add_filter( 'wpseo_editor_specific_replace_vars', '__return_false' );
+		\add_filter( 'wpseo_editor_specific_replace_vars', '__return_false' );
 
 		$expected_replacement_variables = [
 			// Posts types.
@@ -342,7 +340,7 @@ public function test_editor_specific_replacement_variables_filter_with_wrong_ret
 			$this->class_instance->get()
 		);
 
-		remove_filter( 'wpseo_editor_specific_replace_vars', '__return_false' );
+		\remove_filter( 'wpseo_editor_specific_replace_vars', '__return_false' );
 	}
 
 	/**
diff --git a/tests/WP/Admin/Exceptions/test-file-size-exception.php b/tests/WP/Admin/Exceptions/File_Size_Exception_Test.php
similarity index 87%
rename from tests/WP/Admin/Exceptions/test-file-size-exception.php
rename to tests/WP/Admin/Exceptions/File_Size_Exception_Test.php
index 93f96c392b7..341fe899bf2 100644
--- a/tests/WP/Admin/Exceptions/test-file-size-exception.php
+++ b/tests/WP/Admin/Exceptions/File_Size_Exception_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Exceptions
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Exceptions;
+
+use WPSEO_File_Size_Exception;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_File_Size_Exception_Test extends TestCase {
+class File_Size_Exception_Test extends TestCase {
 
 	/**
 	 * Tests that the externally hosted error message is as expected.
diff --git a/tests/WP/Admin/test-class-gutenberg-compatibility.php b/tests/WP/Admin/Gutenberg_Compatibility_Test.php
similarity index 97%
rename from tests/WP/Admin/test-class-gutenberg-compatibility.php
rename to tests/WP/Admin/Gutenberg_Compatibility_Test.php
index afdde282173..c08c9571880 100644
--- a/tests/WP/Admin/test-class-gutenberg-compatibility.php
+++ b/tests/WP/Admin/Gutenberg_Compatibility_Test.php
@@ -1,9 +1,6 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin
- */
+
+namespace Yoast\WP\SEO\Tests\WP\Admin;
 
 use Yoast\WP\SEO\Tests\WP\Doubles\Admin\Gutenberg_Compatibility_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
@@ -11,7 +8,7 @@
 /**
  * Unit Test Class.
  */
-class WPSEO_Gutenberg_Compatibility_Test extends TestCase {
+class Gutenberg_Compatibility_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
diff --git a/tests/WP/Admin/Import/test-class-import-aioseo.php b/tests/WP/Admin/Import/AIOSEO_Test.php
similarity index 67%
rename from tests/WP/Admin/Import/test-class-import-aioseo.php
rename to tests/WP/Admin/Import/AIOSEO_Test.php
index 1a8bf19e6c8..546f23a8e2a 100644
--- a/tests/WP/Admin/Import/test-class-import-aioseo.php
+++ b/tests/WP/Admin/Import/AIOSEO_Test.php
@@ -1,16 +1,18 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use wpdb;
+use WPSEO_Import_AIOSEO;
+use WPSEO_Import_Status;
+use WPSEO_Meta;
+use WPSEO_Plugin_Importers;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test importing meta data from AIOSEO.
  */
-class WPSEO_Import_AIOSEO_Test extends TestCase {
+class AIOSEO_Test extends TestCase {
 
 	/**
 	 * Holds the class instance.
@@ -43,7 +45,7 @@ public function test_plugin_name() {
 	 * @covers WPSEO_Plugin_Importers::get
 	 */
 	public function test_importer_registered() {
-		$this->assertContains( 'WPSEO_Import_AIOSEO', WPSEO_Plugin_Importers::get() );
+		$this->assertContains( WPSEO_Import_AIOSEO::class, WPSEO_Plugin_Importers::get() );
 	}
 
 	/**
@@ -93,12 +95,12 @@ public function test_import_with_data() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
-		$opengraph_image = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
-		$opengraph_title = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$opengraph_image = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
+		$opengraph_title = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
 
 		$this->assertEquals( 'Test title', $seo_title );
 		$this->assertEquals( 'Test description', $seo_desc );
@@ -125,8 +127,8 @@ public function test_import_without_rights_to_temp_table() {
 		// Save for later return.
 		$original_wpdb = $wpdb;
 
-		$wpdb = $this->getMockBuilder( 'wpdb' )
-			->setConstructorArgs( [ DB_USER, DB_PASSWORD, DB_NAME, DB_HOST ] )
+		$wpdb = $this->getMockBuilder( wpdb::class )
+			->setConstructorArgs( [ \DB_USER, \DB_PASSWORD, \DB_NAME, \DB_HOST ] )
 			->setMethods( [ 'query' ] )
 			->getMock();
 		$wpdb->expects( $this->any() )
@@ -157,12 +159,12 @@ public function test_import_without_overwriting_data() {
 		$post_id = $this->setup_post( true );
 		$result  = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
-		$opengraph_image = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
-		$opengraph_title = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$opengraph_image = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
+		$opengraph_title = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
 
 		$this->assertEquals( 'Test title', $seo_title );
 		$this->assertEquals( 'Existing Yoast SEO Test description', $seo_desc );
@@ -193,8 +195,8 @@ public function test_cleanup() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_cleanup();
 
-		$seo_title = get_post_meta( $post_id, '_aioseop_title', true );
-		$seo_desc  = get_post_meta( $post_id, '_aioseop_description', true );
+		$seo_title = \get_post_meta( $post_id, '_aioseop_title', true );
+		$seo_desc  = \get_post_meta( $post_id, '_aioseop_description', true );
 
 		$this->assertEquals( $seo_title, false );
 		$this->assertEquals( $seo_desc, false );
@@ -215,8 +217,8 @@ public function test_cleanup_gone_bad() {
 		global $wpdb;
 		$original_wpdb = $wpdb;
 
-		$wpdb = $this->getMockBuilder( 'wpdb' )
-			->setConstructorArgs( [ DB_USER, DB_PASSWORD, DB_NAME, DB_HOST ] )
+		$wpdb = $this->getMockBuilder( wpdb::class )
+			->setConstructorArgs( [ \DB_USER, \DB_PASSWORD, \DB_NAME, \DB_HOST ] )
 			->setMethods( [ 'query' ] )
 			->getMock();
 		$wpdb->expects( $this->any() )
@@ -252,16 +254,16 @@ private function status( $action, $status ) {
 	 */
 	private function setup_post( $pre_existing_yoast_data = false ) {
 		$post_id = $this->factory()->post->create();
-		update_post_meta( $post_id, '_aioseop_title', 'Test title' );
-		update_post_meta( $post_id, '_aioseop_description', 'Test description' );
-		update_post_meta( $post_id, '_aioseop_noindex', 'on' );
-		update_post_meta( $post_id, '_aioseop_nofollow', 'on' );
-		update_post_meta( $post_id, '_aioseop_opengraph_settings', 'a:15:{s:32:"aioseop_opengraph_settings_title";s:22:"OpenGraph AIOSEO title";s:31:"aioseop_opengraph_settings_desc";s:28:"OpenGraph AIOSEO description";s:36:"aioseop_opengraph_settings_customimg";s:73:"http://local.wordpress.test/wp-content/uploads/2018/01/actionable-seo.png";s:37:"aioseop_opengraph_settings_imagewidth";s:0:"";s:38:"aioseop_opengraph_settings_imageheight";s:0:"";s:32:"aioseop_opengraph_settings_video";s:0:"";s:37:"aioseop_opengraph_settings_videowidth";s:0:"";s:38:"aioseop_opengraph_settings_videoheight";s:0:"";s:35:"aioseop_opengraph_settings_category";s:8:"activity";s:34:"aioseop_opengraph_settings_section";s:0:"";s:30:"aioseop_opengraph_settings_tag";s:0:"";s:34:"aioseop_opengraph_settings_setcard";s:7:"summary";s:44:"aioseop_opengraph_settings_customimg_twitter";s:73:"http://local.wordpress.test/wp-content/uploads/2018/01/actionable-seo.png";s:44:"aioseop_opengraph_settings_customimg_checker";s:1:"1";s:32:"aioseop_opengraph_settings_image";s:73:"http://local.wordpress.test/wp-content/uploads/2018/01/actionable-seo.png";}' );
+		\update_post_meta( $post_id, '_aioseop_title', 'Test title' );
+		\update_post_meta( $post_id, '_aioseop_description', 'Test description' );
+		\update_post_meta( $post_id, '_aioseop_noindex', 'on' );
+		\update_post_meta( $post_id, '_aioseop_nofollow', 'on' );
+		\update_post_meta( $post_id, '_aioseop_opengraph_settings', 'a:15:{s:32:"aioseop_opengraph_settings_title";s:22:"OpenGraph AIOSEO title";s:31:"aioseop_opengraph_settings_desc";s:28:"OpenGraph AIOSEO description";s:36:"aioseop_opengraph_settings_customimg";s:73:"http://local.wordpress.test/wp-content/uploads/2018/01/actionable-seo.png";s:37:"aioseop_opengraph_settings_imagewidth";s:0:"";s:38:"aioseop_opengraph_settings_imageheight";s:0:"";s:32:"aioseop_opengraph_settings_video";s:0:"";s:37:"aioseop_opengraph_settings_videowidth";s:0:"";s:38:"aioseop_opengraph_settings_videoheight";s:0:"";s:35:"aioseop_opengraph_settings_category";s:8:"activity";s:34:"aioseop_opengraph_settings_section";s:0:"";s:30:"aioseop_opengraph_settings_tag";s:0:"";s:34:"aioseop_opengraph_settings_setcard";s:7:"summary";s:44:"aioseop_opengraph_settings_customimg_twitter";s:73:"http://local.wordpress.test/wp-content/uploads/2018/01/actionable-seo.png";s:44:"aioseop_opengraph_settings_customimg_checker";s:1:"1";s:32:"aioseop_opengraph_settings_image";s:73:"http://local.wordpress.test/wp-content/uploads/2018/01/actionable-seo.png";}' );
 
 		if ( $pre_existing_yoast_data ) {
-			update_post_meta( $post_id, '_yoast_wpseo_metadesc', 'Existing Yoast SEO Test description' );
-			update_post_meta( $post_id, '_yoast_wpseo_meta-robots-noindex', 0 );
-			update_post_meta( $post_id, '_yoast_wpseo_opengraph-title', 'Pre-existing Yoast SEO test OpenGraph title' );
+			\update_post_meta( $post_id, '_yoast_wpseo_metadesc', 'Existing Yoast SEO Test description' );
+			\update_post_meta( $post_id, '_yoast_wpseo_meta-robots-noindex', 0 );
+			\update_post_meta( $post_id, '_yoast_wpseo_opengraph-title', 'Pre-existing Yoast SEO test OpenGraph title' );
 		}
 		return $post_id;
 	}
diff --git a/tests/WP/Admin/Import/test-class-import-greg-high-performance-seo.php b/tests/WP/Admin/Import/Greg_SEO_Test.php
similarity index 82%
rename from tests/WP/Admin/Import/test-class-import-greg-high-performance-seo.php
rename to tests/WP/Admin/Import/Greg_SEO_Test.php
index 0683c0b6370..6b7416e22d1 100644
--- a/tests/WP/Admin/Import/test-class-import-greg-high-performance-seo.php
+++ b/tests/WP/Admin/Import/Greg_SEO_Test.php
@@ -1,16 +1,17 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use WPSEO_Import_Greg_SEO;
+use WPSEO_Import_Status;
+use WPSEO_Meta;
+use WPSEO_Plugin_Importers;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test importing meta data from Greg's High Performance SEO.
  */
-class WPSEO_Import_Greg_SEO_Test extends TestCase {
+class Greg_SEO_Test extends TestCase {
 
 	/**
 	 * Holds the class instance.
@@ -43,7 +44,7 @@ public function test_plugin_name() {
 	 * @covers WPSEO_Plugin_Importers::get
 	 */
 	public function test_importer_registered() {
-		$this->assertContains( 'WPSEO_Import_Greg_SEO', WPSEO_Plugin_Importers::get() );
+		$this->assertContains( WPSEO_Import_Greg_SEO::class, WPSEO_Plugin_Importers::get() );
 	}
 
 	/**
@@ -89,8 +90,8 @@ public function test_import() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_import();
 
-		$seo_title = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$seo_title = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
 
 		$this->assertEquals( $seo_title, 'Test title' );
 		$this->assertEquals( $seo_desc, 'Test description' );
@@ -116,8 +117,8 @@ public function test_cleanup() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_cleanup();
 
-		$seo_title = get_post_meta( $post_id, '_su_title', true );
-		$seo_desc  = get_post_meta( $post_id, '_su_description', true );
+		$seo_title = \get_post_meta( $post_id, '_su_title', true );
+		$seo_desc  = \get_post_meta( $post_id, '_su_description', true );
 
 		$this->assertEquals( $seo_title, false );
 		$this->assertEquals( $seo_desc, false );
@@ -143,8 +144,8 @@ private function status( $action, $status ) {
 	 */
 	private function setup_post() {
 		$post_id = $this->factory()->post->create();
-		update_post_meta( $post_id, '_ghpseo_secondary_title', 'Test title' );
-		update_post_meta( $post_id, '_ghpseo_alternative_description', 'Test description' );
+		\update_post_meta( $post_id, '_ghpseo_secondary_title', 'Test title' );
+		\update_post_meta( $post_id, '_ghpseo_alternative_description', 'Test description' );
 
 		return $post_id;
 	}
diff --git a/tests/WP/Admin/Import/test-class-import-headspace.php b/tests/WP/Admin/Import/HeadSpace_Test.php
similarity index 82%
rename from tests/WP/Admin/Import/test-class-import-headspace.php
rename to tests/WP/Admin/Import/HeadSpace_Test.php
index bd18825c10a..d723156a7ab 100644
--- a/tests/WP/Admin/Import/test-class-import-headspace.php
+++ b/tests/WP/Admin/Import/HeadSpace_Test.php
@@ -1,16 +1,17 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use WPSEO_Import_HeadSpace;
+use WPSEO_Import_Status;
+use WPSEO_Meta;
+use WPSEO_Plugin_Importers;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test importing meta data from HeadSpace.
  */
-class WPSEO_Import_HeadSpace_Test extends TestCase {
+class HeadSpace_Test extends TestCase {
 
 	/**
 	 * Holds the class instance.
@@ -43,7 +44,7 @@ public function test_plugin_name() {
 	 * @covers WPSEO_Plugin_Importers::get
 	 */
 	public function test_importer_registered() {
-		$this->assertContains( 'WPSEO_Import_HeadSpace', WPSEO_Plugin_Importers::get() );
+		$this->assertContains( WPSEO_Import_HeadSpace::class, WPSEO_Plugin_Importers::get() );
 	}
 
 	/**
@@ -90,8 +91,8 @@ public function test_import_with_data() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_import();
 
-		$seo_title = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$seo_title = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
 
 		$this->assertEquals( $seo_title, 'Test title' );
 		$this->assertEquals( $seo_desc, 'Test description' );
@@ -118,8 +119,8 @@ public function test_cleanup() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_cleanup();
 
-		$seo_title = get_post_meta( $post_id, '_headspace_page_title', true );
-		$seo_desc  = get_post_meta( $post_id, '_headspace_description', true );
+		$seo_title = \get_post_meta( $post_id, '_headspace_page_title', true );
+		$seo_desc  = \get_post_meta( $post_id, '_headspace_description', true );
 
 		$this->assertEquals( $seo_title, false );
 		$this->assertEquals( $seo_desc, false );
@@ -145,8 +146,8 @@ private function status( $action, $status ) {
 	 */
 	private function setup_post() {
 		$post_id = $this->factory()->post->create();
-		update_post_meta( $post_id, '_headspace_page_title', 'Test title' );
-		update_post_meta( $post_id, '_headspace_description', 'Test description' );
+		\update_post_meta( $post_id, '_headspace_page_title', 'Test title' );
+		\update_post_meta( $post_id, '_headspace_description', 'Test description' );
 
 		return $post_id;
 	}
diff --git a/tests/WP/Admin/Import/test-class-import-jetpack.php b/tests/WP/Admin/Import/Jetpack_SEO_Test.php
similarity index 86%
rename from tests/WP/Admin/Import/test-class-import-jetpack.php
rename to tests/WP/Admin/Import/Jetpack_SEO_Test.php
index bee54b58731..9c9337c61f4 100644
--- a/tests/WP/Admin/Import/test-class-import-jetpack.php
+++ b/tests/WP/Admin/Import/Jetpack_SEO_Test.php
@@ -1,16 +1,17 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use WPSEO_Import_Jetpack_SEO;
+use WPSEO_Import_Status;
+use WPSEO_Meta;
+use WPSEO_Plugin_Importers;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test importing meta data from Jetpack SEO.
  */
-class WPSEO_Import_Jetpack_SEO_Test extends TestCase {
+class Jetpack_SEO_Test extends TestCase {
 
 	/**
 	 * Holds the class instance.
@@ -43,7 +44,7 @@ public function test_plugin_name() {
 	 * @covers WPSEO_Plugin_Importers::get
 	 */
 	public function test_importer_registered() {
-		$this->assertContains( 'WPSEO_Import_Jetpack_SEO', WPSEO_Plugin_Importers::get() );
+		$this->assertContains( WPSEO_Import_Jetpack_SEO::class, WPSEO_Plugin_Importers::get() );
 	}
 
 	/**
@@ -89,7 +90,7 @@ public function test_import() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_import();
 
-		$seo_desc = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$seo_desc = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
 
 		$this->assertEquals( $seo_desc, 'Test description' );
 		$this->assertEquals( $this->status( 'import', true ), $result );
@@ -115,7 +116,7 @@ public function test_cleanup() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_cleanup();
 
-		$seo_desc = get_post_meta( $post_id, 'advanced_seo_description', true );
+		$seo_desc = \get_post_meta( $post_id, 'advanced_seo_description', true );
 
 		$this->assertEquals( $seo_desc, false );
 		$this->assertEquals( $this->status( 'cleanup', true ), $result );
@@ -140,7 +141,7 @@ private function status( $action, $status ) {
 	 */
 	private function setup_post() {
 		$post_id = $this->factory()->post->create();
-		update_post_meta( $post_id, 'advanced_seo_description', 'Test description' );
+		\update_post_meta( $post_id, 'advanced_seo_description', 'Test description' );
 
 		return $post_id;
 	}
diff --git a/tests/WP/Admin/Import/test-class-import-platinum-seo-pack.php b/tests/WP/Admin/Import/Platinum_SEO_Test.php
similarity index 79%
rename from tests/WP/Admin/Import/test-class-import-platinum-seo-pack.php
rename to tests/WP/Admin/Import/Platinum_SEO_Test.php
index da20d5664d5..ddadd842614 100644
--- a/tests/WP/Admin/Import/test-class-import-platinum-seo-pack.php
+++ b/tests/WP/Admin/Import/Platinum_SEO_Test.php
@@ -1,16 +1,17 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use WPSEO_Import_Platinum_SEO;
+use WPSEO_Import_Status;
+use WPSEO_Meta;
+use WPSEO_Plugin_Importers;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test importing meta data from Platinum SEO.
  */
-class WPSEO_Import_Platinum_SEO_Test extends TestCase {
+class Platinum_SEO_Test extends TestCase {
 
 	/**
 	 * Holds the class instance.
@@ -43,7 +44,7 @@ public function test_plugin_name() {
 	 * @covers WPSEO_Plugin_Importers::get
 	 */
 	public function test_importer_registered() {
-		$this->assertContains( 'WPSEO_Import_Platinum_SEO', WPSEO_Plugin_Importers::get() );
+		$this->assertContains( WPSEO_Import_Platinum_SEO::class, WPSEO_Plugin_Importers::get() );
 	}
 
 	/**
@@ -92,10 +93,10 @@ public function test_import() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
 
 		$this->assertEquals( 'Test title', $seo_title );
 		$this->assertEquals( 'Test description', $seo_desc );
@@ -123,8 +124,8 @@ public function test_cleanup() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_cleanup();
 
-		$seo_title = get_post_meta( $post_id, 'title', true );
-		$seo_desc  = get_post_meta( $post_id, 'description', true );
+		$seo_title = \get_post_meta( $post_id, 'title', true );
+		$seo_desc  = \get_post_meta( $post_id, 'description', true );
 
 		$this->assertEquals( $seo_title, false );
 		$this->assertEquals( $seo_desc, false );
@@ -150,9 +151,9 @@ private function status( $action, $status ) {
 	 */
 	private function setup_post() {
 		$post_id = $this->factory()->post->create();
-		update_post_meta( $post_id, 'title', 'Test title' );
-		update_post_meta( $post_id, 'description', 'Test description' );
-		update_post_meta( $post_id, 'robotsmeta', 'noindex,nofollow' );
+		\update_post_meta( $post_id, 'title', 'Test title' );
+		\update_post_meta( $post_id, 'description', 'Test description' );
+		\update_post_meta( $post_id, 'robotsmeta', 'noindex,nofollow' );
 
 		return $post_id;
 	}
diff --git a/tests/WP/Admin/Import/test-class-importers.php b/tests/WP/Admin/Import/Plugin_Importers_Test.php
similarity index 69%
rename from tests/WP/Admin/Import/test-class-importers.php
rename to tests/WP/Admin/Import/Plugin_Importers_Test.php
index ae9f5419a68..7cafcf34c5e 100644
--- a/tests/WP/Admin/Import/test-class-importers.php
+++ b/tests/WP/Admin/Import/Plugin_Importers_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use WPSEO_Plugin_Importers;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test whether we register our plugin importers.
  */
-class WPSEO_Plugin_Importers_Test extends TestCase {
+class Plugin_Importers_Test extends TestCase {
 
 	/**
 	 * Makes sure we can get a list of importers.
diff --git a/tests/WP/Admin/Import/test-class-import-plugin.php b/tests/WP/Admin/Import/Plugin_Test.php
similarity index 91%
rename from tests/WP/Admin/Import/test-class-import-plugin.php
rename to tests/WP/Admin/Import/Plugin_Test.php
index 0fc5a9bbe14..be7c2522bce 100644
--- a/tests/WP/Admin/Import/test-class-import-plugin.php
+++ b/tests/WP/Admin/Import/Plugin_Test.php
@@ -1,16 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use WPSEO_Import_AIOSEO;
+use WPSEO_Import_Plugin;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Tests for our wrapper import class.
  */
-class WPSEO_Import_Plugin_Test extends TestCase {
+class Plugin_Test extends TestCase {
 
 	/**
 	 * Test message for detect without data.
@@ -100,8 +99,8 @@ public function test_cleanup_with_data() {
 	 */
 	private function setup_post() {
 		$post_id = $this->factory()->post->create();
-		update_post_meta( $post_id, '_aioseop_title', 'Test title' );
-		update_post_meta( $post_id, '_aioseop_description', 'Test description' );
+		\update_post_meta( $post_id, '_aioseop_title', 'Test title' );
+		\update_post_meta( $post_id, '_aioseop_description', 'Test description' );
 
 		return $post_id;
 	}
diff --git a/tests/WP/Admin/Import/test-class-import-detector.php b/tests/WP/Admin/Import/Plugins_Detector_Test.php
similarity index 76%
rename from tests/WP/Admin/Import/test-class-import-detector.php
rename to tests/WP/Admin/Import/Plugins_Detector_Test.php
index 96279ac3d5d..f08498ca7d2 100644
--- a/tests/WP/Admin/Import/test-class-import-detector.php
+++ b/tests/WP/Admin/Import/Plugins_Detector_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use WPSEO_Import_Plugins_Detector;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test whether we can detect plugin data to import successfully.
  */
-class WPSEO_Import_External_Detector_Test extends TestCase {
+class Plugins_Detector_Test extends TestCase {
 
 	/**
 	 * Test whether we can return properly when there's no plugin data.
@@ -44,8 +42,8 @@ public function test_detect_with_data() {
 	 */
 	private function setup_post() {
 		$post_id = $this->factory()->post->create();
-		update_post_meta( $post_id, '_aioseop_title', 'Test title' );
-		update_post_meta( $post_id, '_aioseop_description', 'Test description' );
+		\update_post_meta( $post_id, '_aioseop_title', 'Test title' );
+		\update_post_meta( $post_id, '_aioseop_description', 'Test description' );
 
 		return $post_id;
 	}
diff --git a/tests/WP/Admin/Import/test-class-import-premium-seo-pack.php b/tests/WP/Admin/Import/Premium_SEO_Pack_Test.php
similarity index 81%
rename from tests/WP/Admin/Import/test-class-import-premium-seo-pack.php
rename to tests/WP/Admin/Import/Premium_SEO_Pack_Test.php
index 6360b5487c4..a95287de907 100644
--- a/tests/WP/Admin/Import/test-class-import-premium-seo-pack.php
+++ b/tests/WP/Admin/Import/Premium_SEO_Pack_Test.php
@@ -1,16 +1,18 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use wpdb;
+use WPSEO_Import_Premium_SEO_Pack;
+use WPSEO_Import_Status;
+use WPSEO_Meta;
+use WPSEO_Plugin_Importers;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test importing meta data from AIOSEO.
  */
-class WPSEO_Import_Premium_SEO_Pack_Test extends TestCase {
+class Premium_SEO_Pack_Test extends TestCase {
 
 	/**
 	 * Holds the class instance.
@@ -33,8 +35,8 @@ public function set_up() {
 	public function tear_down() {
 		$this->class_instance->run_cleanup();
 
-		add_filter( 'query', [ $this, '_create_temporary_tables' ] );
-		add_filter( 'query', [ $this, '_drop_temporary_tables' ] );
+		\add_filter( 'query', [ $this, '_create_temporary_tables' ] );
+		\add_filter( 'query', [ $this, '_drop_temporary_tables' ] );
 
 		parent::tear_down();
 	}
@@ -54,7 +56,7 @@ public function test_plugin_name() {
 	 * @covers WPSEO_Plugin_Importers::get
 	 */
 	public function test_importer_registered() {
-		$this->assertContains( 'WPSEO_Import_Premium_SEO_Pack', WPSEO_Plugin_Importers::get() );
+		$this->assertContains( WPSEO_Import_Premium_SEO_Pack::class, WPSEO_Plugin_Importers::get() );
 	}
 
 	/**
@@ -107,13 +109,13 @@ public function test_import_with_data() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
-		$opengraph_image = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
-		$opengraph_title = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
-		$cornerstone     = get_post_meta( $post_id, '_yst_is_cornerstone', true );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$opengraph_image = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
+		$opengraph_title = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
+		$cornerstone     = \get_post_meta( $post_id, '_yst_is_cornerstone', true );
 
 		$this->assertEquals( 'Test title', $seo_title );
 		$this->assertEquals( 'Test description', $seo_desc );
@@ -139,12 +141,12 @@ public function test_import_without_overwriting_data() {
 		$post_id = $this->setup_post( true );
 		$result  = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
-		$opengraph_image = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
-		$opengraph_title = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$opengraph_image = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
+		$opengraph_title = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
 
 		$this->assertEquals( 'Test title', $seo_title );
 		$this->assertEquals( 'Existing Yoast SEO Test description', $seo_desc );
@@ -220,8 +222,8 @@ public function test_cleanup_gone_bad() {
 		global $wpdb;
 		$original_wpdb = $wpdb;
 
-		$wpdb = $this->getMockBuilder( 'wpdb' )
-			->setConstructorArgs( [ DB_USER, DB_PASSWORD, DB_NAME, DB_HOST ] )
+		$wpdb = $this->getMockBuilder( wpdb::class )
+			->setConstructorArgs( [ \DB_USER, \DB_PASSWORD, \DB_NAME, \DB_HOST ] )
 			->setMethods( [ 'query', 'get_var' ] )
 			->getMock();
 		$wpdb->expects( $this->any() )
@@ -278,9 +280,9 @@ private function setup_post( $pre_existing_yoast_data = false ) {
 		$this->insert_post( $post_id, $blob );
 
 		if ( $pre_existing_yoast_data ) {
-			update_post_meta( $post_id, '_yoast_wpseo_metadesc', 'Existing Yoast SEO Test description' );
-			update_post_meta( $post_id, '_yoast_wpseo_meta-robots-noindex', 0 );
-			update_post_meta( $post_id, '_yoast_wpseo_opengraph-title', 'Pre-existing Yoast SEO test OpenGraph title' );
+			\update_post_meta( $post_id, '_yoast_wpseo_metadesc', 'Existing Yoast SEO Test description' );
+			\update_post_meta( $post_id, '_yoast_wpseo_meta-robots-noindex', 0 );
+			\update_post_meta( $post_id, '_yoast_wpseo_opengraph-title', 'Pre-existing Yoast SEO test OpenGraph title' );
 		}
 
 		return $post_id;
@@ -294,7 +296,7 @@ private function setup_post( $pre_existing_yoast_data = false ) {
 	 * @return array Complete array
 	 */
 	private function build_data_blob( $data = [] ) {
-		return array_merge(
+		return \array_merge(
 			[
 				'doseo'          => 1,
 				'noindex'        => 0,
@@ -342,11 +344,11 @@ private function insert_post( $post_id, $blob ) {
 					%s, 
 					%s
 				);',
-				get_current_blog_id(),
+				\get_current_blog_id(),
 				$post_id,
-				get_permalink( $post_id ),
-				md5( get_permalink( $post_id ) ),
-				serialize( $blob )
+				\get_permalink( $post_id ),
+				\md5( \get_permalink( $post_id ) ),
+				\serialize( $blob )
 			)
 		);
 	}
@@ -356,7 +358,7 @@ private function insert_post( $post_id, $blob ) {
 	 */
 	private function create_table() {
 		// We need to test creating and dropping tables, so we can't have this.
-		remove_all_filters( 'query' );
+		\remove_all_filters( 'query' );
 
 		global $wpdb;
 		$wpdb->query(
diff --git a/tests/WP/Admin/Import/test-class-import-rankmath.php b/tests/WP/Admin/Import/RankMath_Test.php
similarity index 75%
rename from tests/WP/Admin/Import/test-class-import-rankmath.php
rename to tests/WP/Admin/Import/RankMath_Test.php
index 015e14c0641..363bd47d813 100644
--- a/tests/WP/Admin/Import/test-class-import-rankmath.php
+++ b/tests/WP/Admin/Import/RankMath_Test.php
@@ -1,16 +1,18 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use WPSEO_Import_RankMath;
+use WPSEO_Import_Status;
+use WPSEO_Meta;
+use WPSEO_Options;
+use WPSEO_Plugin_Importers;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test importing meta data from SEO Framework.
  */
-class RankMath_Import_SEO_Framework_Test extends TestCase {
+class RankMath_Test extends TestCase {
 
 	/**
 	 * Holds the class instance.
@@ -43,7 +45,7 @@ public function test_plugin_name() {
 	 * @covers WPSEO_Plugin_Importers::get
 	 */
 	public function test_importer_registered() {
-		$this->assertContains( 'WPSEO_Import_RankMath', WPSEO_Plugin_Importers::get() );
+		$this->assertContains( WPSEO_Import_RankMath::class, WPSEO_Plugin_Importers::get() );
 	}
 
 	/**
@@ -91,12 +93,12 @@ public function test_import() {
 		$this->setup_options();
 		$result = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
-		$twitter_title   = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'twitter-title', true );
-		$twitter_desc    = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'twitter-description', true );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$twitter_title   = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'twitter-title', true );
+		$twitter_desc    = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'twitter-description', true );
 
 		$homepage_title      = WPSEO_Options::get( 'title-home-wpseo' );
 		$homepage_desc       = WPSEO_Options::get( 'metadesc-home-wpseo' );
@@ -134,10 +136,10 @@ public function test_cleanup() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_cleanup();
 
-		$seo_title = get_post_meta( $post_id, 'rank_math_title', true );
-		$seo_desc  = get_post_meta( $post_id, 'rank_math_description', true );
+		$seo_title = \get_post_meta( $post_id, 'rank_math_title', true );
+		$seo_desc  = \get_post_meta( $post_id, 'rank_math_description', true );
 
-		$title_option = get_option( 'rank-math-options-titles' );
+		$title_option = \get_option( 'rank-math-options-titles' );
 
 		$this->assertEquals( $title_option, false );
 		$this->assertEquals( $seo_title, false );
@@ -165,11 +167,11 @@ private function status( $action, $status ) {
 	 */
 	private function setup_post() {
 		$post_id = $this->factory()->post->create();
-		update_post_meta( $post_id, 'rank_math_title', 'Test title' );
-		update_post_meta( $post_id, 'rank_math_description', 'Test description' );
-		update_post_meta( $post_id, 'rank_math_robots', [ 'noindex', 'nofollow' ] );
-		update_post_meta( $post_id, 'rank_math_twitter_title', 'Test Twitter title' );
-		update_post_meta( $post_id, 'rank_math_twitter_description', 'Test Twitter description' );
+		\update_post_meta( $post_id, 'rank_math_title', 'Test title' );
+		\update_post_meta( $post_id, 'rank_math_description', 'Test description' );
+		\update_post_meta( $post_id, 'rank_math_robots', [ 'noindex', 'nofollow' ] );
+		\update_post_meta( $post_id, 'rank_math_twitter_title', 'Test Twitter title' );
+		\update_post_meta( $post_id, 'rank_math_twitter_description', 'Test Twitter description' );
 
 		return $post_id;
 	}
@@ -178,7 +180,7 @@ private function setup_post() {
 	 * Sets up a fake RankMath settings array.
 	 */
 	private function setup_options() {
-		update_option(
+		\update_option(
 			'rank-math-options-titles',
 			[
 				'homepage_title'       => 'Test homepage title',
diff --git a/tests/WP/Admin/Import/test-class-import-seopressor.php b/tests/WP/Admin/Import/SEOPressor_Test.php
similarity index 76%
rename from tests/WP/Admin/Import/test-class-import-seopressor.php
rename to tests/WP/Admin/Import/SEOPressor_Test.php
index 84d4e3d9003..20efd2b5cd8 100644
--- a/tests/WP/Admin/Import/test-class-import-seopressor.php
+++ b/tests/WP/Admin/Import/SEOPressor_Test.php
@@ -1,16 +1,17 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use WPSEO_Import_SEOPressor;
+use WPSEO_Import_Status;
+use WPSEO_Meta;
+use WPSEO_Plugin_Importers;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test importing meta data from SEOPressor.
  */
-class WPSEO_Import_SEOPressor_Test extends TestCase {
+class SEOPressor_Test extends TestCase {
 
 	/**
 	 * Holds the class instance.
@@ -43,7 +44,7 @@ public function test_plugin_name() {
 	 * @covers WPSEO_Plugin_Importers::get
 	 */
 	public function test_importer_registered() {
-		$this->assertContains( 'WPSEO_Import_SEOPressor', WPSEO_Plugin_Importers::get() );
+		$this->assertContains( WPSEO_Import_SEOPressor::class, WPSEO_Plugin_Importers::get() );
 	}
 
 	/**
@@ -92,12 +93,12 @@ public function test_import() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
-		$focus_kw        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'focuskw', true );
-		$extra_focus_kw  = json_decode( get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'focuskeywords', true ) );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$focus_kw        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'focuskw', true );
+		$extra_focus_kw  = \json_decode( \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'focuskeywords', true ) );
 
 		$this->assertEquals( 'Test title', $seo_title );
 		$this->assertEquals( 'Test description', $seo_desc );
@@ -127,7 +128,7 @@ public function test_cleanup() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_cleanup();
 
-		$seo_options = get_post_meta( $post_id, '_seop_settings', true );
+		$seo_options = \get_post_meta( $post_id, '_seop_settings', true );
 
 		$this->assertEquals( $seo_options, false );
 		$this->assertEquals( $this->status( 'cleanup', true ), $result );
@@ -157,10 +158,10 @@ private function setup_post() {
 			'meta_description' => 'Test description',
 			'meta_rules'       => 'noindex#|#|#nofollow',
 		];
-		update_post_meta( $post_id, '_seop_settings', $settings );
-		update_post_meta( $post_id, '_seop_kw_1', 'Test focus kw' );
-		update_post_meta( $post_id, '_seop_kw_2', 'Test focus kw 2' );
-		update_post_meta( $post_id, '_seop_kw_3', 'Test focus kw 3' );
+		\update_post_meta( $post_id, '_seop_settings', $settings );
+		\update_post_meta( $post_id, '_seop_kw_1', 'Test focus kw' );
+		\update_post_meta( $post_id, '_seop_kw_2', 'Test focus kw 2' );
+		\update_post_meta( $post_id, '_seop_kw_3', 'Test focus kw 3' );
 
 		return $post_id;
 	}
diff --git a/tests/WP/Admin/Import/test-class-import-seo-framework.php b/tests/WP/Admin/Import/SEO_Framework_Test.php
similarity index 72%
rename from tests/WP/Admin/Import/test-class-import-seo-framework.php
rename to tests/WP/Admin/Import/SEO_Framework_Test.php
index 03ee0828bed..440c4c02950 100644
--- a/tests/WP/Admin/Import/test-class-import-seo-framework.php
+++ b/tests/WP/Admin/Import/SEO_Framework_Test.php
@@ -1,16 +1,17 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use WPSEO_Import_SEO_Framework;
+use WPSEO_Import_Status;
+use WPSEO_Meta;
+use WPSEO_Plugin_Importers;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test importing meta data from SEO Framework.
  */
-class WPSEO_Import_SEO_Framework_Test extends TestCase {
+class SEO_Framework_Test extends TestCase {
 
 	/**
 	 * Holds the class instance.
@@ -43,7 +44,7 @@ public function test_plugin_name() {
 	 * @covers WPSEO_Plugin_Importers::get
 	 */
 	public function test_importer_registered() {
-		$this->assertContains( 'WPSEO_Import_SEO_Framework', WPSEO_Plugin_Importers::get() );
+		$this->assertContains( WPSEO_Import_SEO_Framework::class, WPSEO_Plugin_Importers::get() );
 	}
 
 	/**
@@ -89,12 +90,12 @@ public function test_import() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
-		$twitter_title   = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'twitter-title', true );
-		$twitter_desc    = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'twitter-description', true );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$twitter_title   = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'twitter-title', true );
+		$twitter_desc    = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'twitter-description', true );
 
 		$this->assertEquals( 1, $robots_noindex );
 		$this->assertEquals( 1, $robots_nofollow );
@@ -124,8 +125,8 @@ public function test_cleanup() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_cleanup();
 
-		$seo_title = get_post_meta( $post_id, '_su_title', true );
-		$seo_desc  = get_post_meta( $post_id, '_su_description', true );
+		$seo_title = \get_post_meta( $post_id, '_su_title', true );
+		$seo_desc  = \get_post_meta( $post_id, '_su_description', true );
 
 		$this->assertEquals( $seo_title, false );
 		$this->assertEquals( $seo_desc, false );
@@ -152,12 +153,12 @@ private function status( $action, $status ) {
 	 */
 	private function setup_post() {
 		$post_id = $this->factory()->post->create();
-		update_post_meta( $post_id, '_genesis_title', 'Test title' );
-		update_post_meta( $post_id, '_genesis_description', 'Test description' );
-		update_post_meta( $post_id, '_genesis_noindex', 1 );
-		update_post_meta( $post_id, '_genesis_nofollow', 1 );
-		update_post_meta( $post_id, '_twitter_title', 'Test Twitter title' );
-		update_post_meta( $post_id, '_twitter_description', 'Test Twitter description' );
+		\update_post_meta( $post_id, '_genesis_title', 'Test title' );
+		\update_post_meta( $post_id, '_genesis_description', 'Test description' );
+		\update_post_meta( $post_id, '_genesis_noindex', 1 );
+		\update_post_meta( $post_id, '_genesis_nofollow', 1 );
+		\update_post_meta( $post_id, '_twitter_title', 'Test Twitter title' );
+		\update_post_meta( $post_id, '_twitter_description', 'Test Twitter description' );
 
 		return $post_id;
 	}
diff --git a/tests/WP/Admin/Import/test-class-import-settings.php b/tests/WP/Admin/Import/Settings_Test.php
similarity index 92%
rename from tests/WP/Admin/Import/test-class-import-settings.php
rename to tests/WP/Admin/Import/Settings_Test.php
index cf4ea803869..d3ad472bdb3 100644
--- a/tests/WP/Admin/Import/test-class-import-settings.php
+++ b/tests/WP/Admin/Import/Settings_Test.php
@@ -1,10 +1,8 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use WPSEO_Options;
 use Yoast\WP\SEO\Tests\WP\Doubles\Admin\Import_Settings_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
@@ -13,7 +11,7 @@
  *
  * @group imports
  */
-class WPSEO_Import_Settings_Test extends TestCase {
+class Settings_Test extends TestCase {
 
 	/**
 	 * Holds the class instance.
diff --git a/tests/WP/Admin/Import/test-class-import-smartcrawl.php b/tests/WP/Admin/Import/Smartcrawl_SEO_Test.php
similarity index 71%
rename from tests/WP/Admin/Import/test-class-import-smartcrawl.php
rename to tests/WP/Admin/Import/Smartcrawl_SEO_Test.php
index 738d170d8bb..f6d4d6f411e 100644
--- a/tests/WP/Admin/Import/test-class-import-smartcrawl.php
+++ b/tests/WP/Admin/Import/Smartcrawl_SEO_Test.php
@@ -1,16 +1,18 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use wpdb;
+use WPSEO_Import_Smartcrawl_SEO;
+use WPSEO_Import_Status;
+use WPSEO_Meta;
+use WPSEO_Plugin_Importers;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test importing meta data from Smartcrawl_SEO.
  */
-class WPSEO_Import_Smartcrawl_SEO_Test extends TestCase {
+class Smartcrawl_SEO_Test extends TestCase {
 
 	/**
 	 * Holds the class instance.
@@ -43,7 +45,7 @@ public function test_plugin_name() {
 	 * @covers WPSEO_Plugin_Importers::get
 	 */
 	public function test_importer_registered() {
-		$this->assertContains( 'WPSEO_Import_Smartcrawl_SEO', WPSEO_Plugin_Importers::get() );
+		$this->assertContains( WPSEO_Import_Smartcrawl_SEO::class, WPSEO_Plugin_Importers::get() );
 	}
 
 	/**
@@ -95,14 +97,14 @@ public function test_import_with_data() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
-		$opengraph_image = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
-		$opengraph_title = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
-		$twitter_title   = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'twitter-title', true );
-		$focuskw         = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'focuskw', true );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$opengraph_image = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
+		$opengraph_title = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
+		$twitter_title   = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'twitter-title', true );
+		$focuskw         = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'focuskw', true );
 
 		$this->assertEquals( 'Test title', $seo_title );
 		$this->assertEquals( 'Test description', $seo_desc );
@@ -130,14 +132,14 @@ public function test_import_with_data() {
 	 */
 	public function test_import_without_opengraph_data() {
 		$post_id = $this->setup_post();
-		delete_post_meta( $post_id, '_wds_twitter' );
-		delete_post_meta( $post_id, '_wds_opengraph' );
+		\delete_post_meta( $post_id, '_wds_twitter' );
+		\delete_post_meta( $post_id, '_wds_opengraph' );
 		$result = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
 
 		$this->assertEquals( 'Test title', $seo_title );
 		$this->assertEquals( 'Test description', $seo_desc );
@@ -165,8 +167,8 @@ public function test_import_without_rights_to_temp_table() {
 		// Save for later return.
 		$original_wpdb = $wpdb;
 
-		$wpdb = $this->getMockBuilder( 'wpdb' )
-			->setConstructorArgs( [ DB_USER, DB_PASSWORD, DB_NAME, DB_HOST ] )
+		$wpdb = $this->getMockBuilder( wpdb::class )
+			->setConstructorArgs( [ \DB_USER, \DB_PASSWORD, \DB_NAME, \DB_HOST ] )
 			->setMethods( [ 'query' ] )
 			->getMock();
 		$wpdb->expects( $this->any() )
@@ -198,12 +200,12 @@ public function test_import_without_overwriting_data() {
 		$post_id = $this->setup_post( true );
 		$result  = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
-		$opengraph_image = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
-		$opengraph_title = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$opengraph_image = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
+		$opengraph_title = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
 
 		$this->assertEquals( 'Test title', $seo_title );
 		$this->assertEquals( 'Existing Yoast SEO Test description', $seo_desc );
@@ -234,9 +236,9 @@ public function test_cleanup() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_cleanup();
 
-		$seo_title = get_post_meta( $post_id, '_wds_metadesc', true );
-		$seo_desc  = get_post_meta( $post_id, '_wds_title', true );
-		$twitter   = get_post_meta( $post_id, '_wds_twitter', true );
+		$seo_title = \get_post_meta( $post_id, '_wds_metadesc', true );
+		$seo_desc  = \get_post_meta( $post_id, '_wds_title', true );
+		$twitter   = \get_post_meta( $post_id, '_wds_twitter', true );
 
 		$this->assertEquals( $seo_title, false );
 		$this->assertEquals( $seo_desc, false );
@@ -258,8 +260,8 @@ public function test_cleanup_gone_bad() {
 		global $wpdb;
 		$original_wpdb = $wpdb;
 
-		$wpdb = $this->getMockBuilder( 'wpdb' )
-			->setConstructorArgs( [ DB_USER, DB_PASSWORD, DB_NAME, DB_HOST ] )
+		$wpdb = $this->getMockBuilder( wpdb::class )
+			->setConstructorArgs( [ \DB_USER, \DB_PASSWORD, \DB_NAME, \DB_HOST ] )
 			->setMethods( [ 'query' ] )
 			->getMock();
 		$wpdb->expects( $this->any() )
@@ -295,18 +297,18 @@ private function status( $action, $status ) {
 	 */
 	private function setup_post( $pre_existing_yoast_data = false ) {
 		$post_id = $this->factory()->post->create();
-		update_post_meta( $post_id, '_wds_title', 'Test title' );
-		update_post_meta( $post_id, '_wds_metadesc', 'Test description' );
-		update_post_meta( $post_id, '_wds_focus-keywords', 'smartcrawl focuskw' );
-		update_post_meta( $post_id, '_wds_meta-robots-noindex', 1 );
-		update_post_meta( $post_id, '_wds_meta-robots-nofollow', 1 );
-		update_post_meta( $post_id, '_wds_opengraph', 'a:4:{s:8:"disabled";b:0;s:5:"title";s:31:"smartcrawl test opengraph title";s:11:"description";s:30:"smartcrawl test opengraph desc";s:6:"images";a:1:{i:0;s:73:"http://local.wordpress.test/wp-content/uploads/2018/01/actionable-seo.png";}}' );
-		update_post_meta( $post_id, '_wds_twitter', 'a:3:{s:8:"disabled";b:0;s:6:"use_og";b:0;s:5:"title";s:29:"smartcrawl test twitter title";}' );
+		\update_post_meta( $post_id, '_wds_title', 'Test title' );
+		\update_post_meta( $post_id, '_wds_metadesc', 'Test description' );
+		\update_post_meta( $post_id, '_wds_focus-keywords', 'smartcrawl focuskw' );
+		\update_post_meta( $post_id, '_wds_meta-robots-noindex', 1 );
+		\update_post_meta( $post_id, '_wds_meta-robots-nofollow', 1 );
+		\update_post_meta( $post_id, '_wds_opengraph', 'a:4:{s:8:"disabled";b:0;s:5:"title";s:31:"smartcrawl test opengraph title";s:11:"description";s:30:"smartcrawl test opengraph desc";s:6:"images";a:1:{i:0;s:73:"http://local.wordpress.test/wp-content/uploads/2018/01/actionable-seo.png";}}' );
+		\update_post_meta( $post_id, '_wds_twitter', 'a:3:{s:8:"disabled";b:0;s:6:"use_og";b:0;s:5:"title";s:29:"smartcrawl test twitter title";}' );
 
 		if ( $pre_existing_yoast_data ) {
-			update_post_meta( $post_id, '_yoast_wpseo_metadesc', 'Existing Yoast SEO Test description' );
-			update_post_meta( $post_id, '_yoast_wpseo_meta-robots-noindex', 0 );
-			update_post_meta( $post_id, '_yoast_wpseo_opengraph-title', 'Pre-existing Yoast SEO test OpenGraph title' );
+			\update_post_meta( $post_id, '_yoast_wpseo_metadesc', 'Existing Yoast SEO Test description' );
+			\update_post_meta( $post_id, '_yoast_wpseo_meta-robots-noindex', 0 );
+			\update_post_meta( $post_id, '_yoast_wpseo_opengraph-title', 'Pre-existing Yoast SEO test OpenGraph title' );
 		}
 		return $post_id;
 	}
diff --git a/tests/WP/Admin/Import/test-class-import-squirrly.php b/tests/WP/Admin/Import/Squirrly_Test.php
similarity index 78%
rename from tests/WP/Admin/Import/test-class-import-squirrly.php
rename to tests/WP/Admin/Import/Squirrly_Test.php
index 08acc6f2fde..cc6e4c284db 100644
--- a/tests/WP/Admin/Import/test-class-import-squirrly.php
+++ b/tests/WP/Admin/Import/Squirrly_Test.php
@@ -1,16 +1,18 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use wpdb;
+use WPSEO_Import_Squirrly;
+use WPSEO_Import_Status;
+use WPSEO_Meta;
+use WPSEO_Plugin_Importers;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test importing meta data from AIOSEO.
  */
-class WPSEO_Import_Squirrly_Test extends TestCase {
+class Squirrly_Test extends TestCase {
 
 	/**
 	 * Holds the class instance.
@@ -33,8 +35,8 @@ public function set_up() {
 	public function tear_down() {
 		$this->class_instance->run_cleanup();
 
-		add_filter( 'query', [ $this, '_create_temporary_tables' ] );
-		add_filter( 'query', [ $this, '_drop_temporary_tables' ] );
+		\add_filter( 'query', [ $this, '_create_temporary_tables' ] );
+		\add_filter( 'query', [ $this, '_drop_temporary_tables' ] );
 
 		parent::tear_down();
 	}
@@ -54,7 +56,7 @@ public function test_plugin_name() {
 	 * @covers WPSEO_Plugin_Importers::get
 	 */
 	public function test_importer_registered() {
-		$this->assertContains( 'WPSEO_Import_Squirrly', WPSEO_Plugin_Importers::get() );
+		$this->assertContains( WPSEO_Import_Squirrly::class, WPSEO_Plugin_Importers::get() );
 	}
 
 	/**
@@ -107,13 +109,13 @@ public function test_import_with_data() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
-		$opengraph_image = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
-		$opengraph_title = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
-		$cornerstone     = get_post_meta( $post_id, '_yst_is_cornerstone', true );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$opengraph_image = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
+		$opengraph_title = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
+		$cornerstone     = \get_post_meta( $post_id, '_yst_is_cornerstone', true );
 
 		$this->assertEquals( 'Test title', $seo_title );
 		$this->assertEquals( 'Test description', $seo_desc );
@@ -139,12 +141,12 @@ public function test_import_without_overwriting_data() {
 		$post_id = $this->setup_post( true );
 		$result  = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
-		$opengraph_image = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
-		$opengraph_title = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$opengraph_image = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
+		$opengraph_title = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
 
 		$this->assertEquals( 'Test title', $seo_title );
 		$this->assertEquals( 'Existing Yoast SEO Test description', $seo_desc );
@@ -168,16 +170,16 @@ public function test_import_without_overwriting_data() {
 	 */
 	public function test_import_without_focus_keyword() {
 		$post_id = $this->setup_post( true );
-		delete_post_meta( $post_id, '_sq_post_keyword' );
+		\delete_post_meta( $post_id, '_sq_post_keyword' );
 
 		$result = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
-		$opengraph_image = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
-		$opengraph_title = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$opengraph_image = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-image', true );
+		$opengraph_title = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
 
 		$this->assertEquals( 'Test title', $seo_title );
 		$this->assertEquals( 'Existing Yoast SEO Test description', $seo_desc );
@@ -226,7 +228,7 @@ public function test_cleanup_without_data() {
 	 * @covers WPSEO_Import_Squirrly::cleanup
 	 */
 	public function test_cleanup() {
-		remove_all_filters( 'query' );
+		\remove_all_filters( 'query' );
 
 		$this->setup_post();
 		$result = $this->class_instance->run_cleanup();
@@ -254,8 +256,8 @@ public function test_cleanup_gone_bad() {
 		global $wpdb;
 		$original_wpdb = $wpdb;
 
-		$wpdb = $this->getMockBuilder( 'wpdb' )
-			->setConstructorArgs( [ DB_USER, DB_PASSWORD, DB_NAME, DB_HOST ] )
+		$wpdb = $this->getMockBuilder( wpdb::class )
+			->setConstructorArgs( [ \DB_USER, \DB_PASSWORD, \DB_NAME, \DB_HOST ] )
 			->setMethods( [ 'query', 'get_var' ] )
 			->getMock();
 		$wpdb->expects( $this->any() )
@@ -310,12 +312,12 @@ private function setup_post( $pre_existing_yoast_data = false ) {
 			]
 		);
 		$this->insert_post( $post_id, $blob );
-		update_post_meta( $post_id, '_sq_post_keyword', '{"keyword":"squirrly test","update":1521207189}' );
+		\update_post_meta( $post_id, '_sq_post_keyword', '{"keyword":"squirrly test","update":1521207189}' );
 
 		if ( $pre_existing_yoast_data ) {
-			update_post_meta( $post_id, '_yoast_wpseo_metadesc', 'Existing Yoast SEO Test description' );
-			update_post_meta( $post_id, '_yoast_wpseo_meta-robots-noindex', 0 );
-			update_post_meta( $post_id, '_yoast_wpseo_opengraph-title', 'Pre-existing Yoast SEO test OpenGraph title' );
+			\update_post_meta( $post_id, '_yoast_wpseo_metadesc', 'Existing Yoast SEO Test description' );
+			\update_post_meta( $post_id, '_yoast_wpseo_meta-robots-noindex', 0 );
+			\update_post_meta( $post_id, '_yoast_wpseo_opengraph-title', 'Pre-existing Yoast SEO test OpenGraph title' );
 		}
 
 		return $post_id;
@@ -329,7 +331,7 @@ private function setup_post( $pre_existing_yoast_data = false ) {
 	 * @return array Complete array.
 	 */
 	private function build_data_blob( $data = [] ) {
-		return array_merge(
+		return \array_merge(
 			[
 				'doseo'          => 1,
 				'noindex'        => 0,
@@ -377,11 +379,11 @@ private function insert_post( $post_id, $blob ) {
 					%s, 
 					%s
 				);',
-				get_current_blog_id(),
+				\get_current_blog_id(),
 				$post_id,
-				get_permalink( $post_id ),
-				md5( get_permalink( $post_id ) ),
-				serialize( $blob )
+				\get_permalink( $post_id ),
+				\md5( \get_permalink( $post_id ) ),
+				\serialize( $blob )
 			)
 		);
 	}
@@ -391,7 +393,7 @@ private function insert_post( $post_id, $blob ) {
 	 */
 	private function create_table() {
 		// We need to test creating and dropping tables, so we can't have this.
-		remove_all_filters( 'query' );
+		\remove_all_filters( 'query' );
 
 		global $wpdb;
 		$wpdb->query(
diff --git a/tests/WP/Admin/Import/test-class-import-status.php b/tests/WP/Admin/Import/Status_Test.php
similarity index 97%
rename from tests/WP/Admin/Import/test-class-import-status.php
rename to tests/WP/Admin/Import/Status_Test.php
index 7d9b7686800..bd50102d0f0 100644
--- a/tests/WP/Admin/Import/test-class-import-status.php
+++ b/tests/WP/Admin/Import/Status_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use WPSEO_Import_Status;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Tests for our import status object.
  */
-class WPSEO_Import_Status_Test extends TestCase {
+class Status_Test extends TestCase {
 
 	/**
 	 * Tests whether we can set a status message for the detect action.
diff --git a/tests/WP/Admin/Import/test-class-import-ultimate-seo.php b/tests/WP/Admin/Import/Ultimate_SEO_Test.php
similarity index 77%
rename from tests/WP/Admin/Import/test-class-import-ultimate-seo.php
rename to tests/WP/Admin/Import/Ultimate_SEO_Test.php
index b749a8099e1..28543990602 100644
--- a/tests/WP/Admin/Import/test-class-import-ultimate-seo.php
+++ b/tests/WP/Admin/Import/Ultimate_SEO_Test.php
@@ -1,16 +1,17 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use WPSEO_Import_Status;
+use WPSEO_Import_Ultimate_SEO;
+use WPSEO_Meta;
+use WPSEO_Plugin_Importers;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test importing meta data from Ultimate SEO.
  */
-class WPSEO_Import_Ultimate_SEO_Test extends TestCase {
+class Ultimate_SEO_Test extends TestCase {
 
 	/**
 	 * Holds the class instance.
@@ -43,7 +44,7 @@ public function test_plugin_name() {
 	 * @covers WPSEO_Plugin_Importers::get
 	 */
 	public function test_importer_registered() {
-		$this->assertContains( 'WPSEO_Import_Ultimate_SEO', WPSEO_Plugin_Importers::get() );
+		$this->assertContains( WPSEO_Import_Ultimate_SEO::class, WPSEO_Plugin_Importers::get() );
 	}
 
 	/**
@@ -89,10 +90,10 @@ public function test_import() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
 
 		$this->assertEquals( 1, $robots_noindex );
 		$this->assertEquals( 1, $robots_nofollow );
@@ -120,8 +121,8 @@ public function test_cleanup() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_cleanup();
 
-		$seo_title = get_post_meta( $post_id, '_su_title', true );
-		$seo_desc  = get_post_meta( $post_id, '_su_description', true );
+		$seo_title = \get_post_meta( $post_id, '_su_title', true );
+		$seo_desc  = \get_post_meta( $post_id, '_su_description', true );
 
 		$this->assertEquals( $seo_title, false );
 		$this->assertEquals( $seo_desc, false );
@@ -147,10 +148,10 @@ private function status( $action, $status ) {
 	 */
 	private function setup_post() {
 		$post_id = $this->factory()->post->create();
-		update_post_meta( $post_id, '_su_title', 'Test title' );
-		update_post_meta( $post_id, '_su_description', 'Test description' );
-		update_post_meta( $post_id, '_su_meta_robots_noindex', 'on' );
-		update_post_meta( $post_id, '_su_meta_robots_nofollow', 'on' );
+		\update_post_meta( $post_id, '_su_title', 'Test title' );
+		\update_post_meta( $post_id, '_su_description', 'Test description' );
+		\update_post_meta( $post_id, '_su_meta_robots_noindex', 'on' );
+		\update_post_meta( $post_id, '_su_meta_robots_nofollow', 'on' );
 		return $post_id;
 	}
 }
diff --git a/tests/WP/Admin/Import/test-class-import-wpseo.php b/tests/WP/Admin/Import/WPSEO_Test.php
similarity index 78%
rename from tests/WP/Admin/Import/test-class-import-wpseo.php
rename to tests/WP/Admin/Import/WPSEO_Test.php
index ff1e9080eb2..c6336897d81 100644
--- a/tests/WP/Admin/Import/test-class-import-wpseo.php
+++ b/tests/WP/Admin/Import/WPSEO_Test.php
@@ -1,16 +1,18 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use WPSEO_Import_Status;
+use WPSEO_Import_WPSEO;
+use WPSEO_Meta;
+use WPSEO_Plugin_Importers;
+use WPSEO_Taxonomy_Meta;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test importing meta data from wpSEO.de.
  */
-class WPSEO_Import_WPSEO_Test extends TestCase {
+class WPSEO_Test extends TestCase {
 
 	/**
 	 * Holds the class instance.
@@ -43,7 +45,7 @@ public function test_plugin_name() {
 	 * @covers WPSEO_Plugin_Importers::get
 	 */
 	public function test_importer_registered() {
-		$this->assertContains( 'WPSEO_Import_WPSEO', WPSEO_Plugin_Importers::get() );
+		$this->assertContains( WPSEO_Import_WPSEO::class, WPSEO_Plugin_Importers::get() );
 	}
 
 	/**
@@ -91,12 +93,12 @@ public function test_import() {
 		$post_id = $this->setup_data();
 		$result  = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$og_title        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
-		$tw_title        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'twitter-title', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$og_title        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'opengraph-title', true );
+		$tw_title        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'twitter-title', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
 
 		$this->assertEquals( 'Test title', $seo_title );
 		$this->assertEquals( 'Test description', $seo_desc );
@@ -144,10 +146,10 @@ public function test_import_category() {
 	 */
 	public function test_import_faulty_robots() {
 		$post_id = $this->setup_data();
-		update_post_meta( $post_id, '_wpseo_edit_robots', 9 );
+		\update_post_meta( $post_id, '_wpseo_edit_robots', 9 );
 
 		$this->class_instance->run_import();
-		$robots_noindex = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_noindex = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
 		$this->assertEquals( 2, $robots_noindex );
 	}
 
@@ -173,8 +175,8 @@ public function test_cleanup() {
 		$post_id = $this->setup_data();
 		$result  = $this->class_instance->run_cleanup();
 
-		$seo_title = get_post_meta( $post_id, '_wpseo_edit_title', true );
-		$seo_desc  = get_post_meta( $post_id, '_wpseo_edit_description', true );
+		$seo_title = \get_post_meta( $post_id, '_wpseo_edit_title', true );
+		$seo_desc  = \get_post_meta( $post_id, '_wpseo_edit_description', true );
 
 		$this->assertEquals( $seo_title, false );
 		$this->assertEquals( $seo_desc, false );
@@ -200,11 +202,11 @@ private function status( $action, $status ) {
 	 */
 	private function setup_data() {
 		$post_id = $this->factory()->post->create();
-		update_post_meta( $post_id, '_wpseo_edit_title', 'Test title' );
-		update_post_meta( $post_id, '_wpseo_edit_description', 'Test description' );
-		update_post_meta( $post_id, '_wpseo_edit_robots', 5 );
-		update_post_meta( $post_id, '_wpseo_edit_og_title', 'Test OG title' );
-		update_post_meta( $post_id, '_wpseo_edit_twittercard_title', 'Test Twitter title' );
+		\update_post_meta( $post_id, '_wpseo_edit_title', 'Test title' );
+		\update_post_meta( $post_id, '_wpseo_edit_description', 'Test description' );
+		\update_post_meta( $post_id, '_wpseo_edit_robots', 5 );
+		\update_post_meta( $post_id, '_wpseo_edit_og_title', 'Test OG title' );
+		\update_post_meta( $post_id, '_wpseo_edit_twittercard_title', 'Test Twitter title' );
 
 		return $post_id;
 	}
@@ -225,7 +227,7 @@ private function create_category_metadata( $name, $desc, $robots ) {
 				'taxonomy' => 'category',
 			]
 		);
-		update_option( 'wpseo_category_' . $term_id, $desc );
-		update_option( 'wpseo_category_' . $term_id . '_robots', $robots );
+		\update_option( 'wpseo_category_' . $term_id, $desc );
+		\update_option( 'wpseo_category_' . $term_id . '_robots', $robots );
 	}
 }
diff --git a/tests/WP/Admin/Import/test-class-import-wp-meta-seo.php b/tests/WP/Admin/Import/WP_Meta_SEO_Test.php
similarity index 76%
rename from tests/WP/Admin/Import/test-class-import-wp-meta-seo.php
rename to tests/WP/Admin/Import/WP_Meta_SEO_Test.php
index 8dd11c67f5e..a03b9de6921 100644
--- a/tests/WP/Admin/Import/test-class-import-wp-meta-seo.php
+++ b/tests/WP/Admin/Import/WP_Meta_SEO_Test.php
@@ -1,16 +1,17 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use WPSEO_Import_Status;
+use WPSEO_Import_WP_Meta_SEO;
+use WPSEO_Meta;
+use WPSEO_Plugin_Importers;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test importing meta data from WP Meta SEO.
  */
-class WPSEO_Import_WP_Meta_SEO_Test extends TestCase {
+class WP_Meta_SEO_Test extends TestCase {
 
 	/**
 	 * Holds the class instance.
@@ -43,7 +44,7 @@ public function test_plugin_name() {
 	 * @covers WPSEO_Plugin_Importers::get
 	 */
 	public function test_importer_registered() {
-		$this->assertContains( 'WPSEO_Import_WP_Meta_SEO', WPSEO_Plugin_Importers::get() );
+		$this->assertContains( WPSEO_Import_WP_Meta_SEO::class, WPSEO_Plugin_Importers::get() );
 	}
 
 	/**
@@ -89,10 +90,10 @@ public function test_import() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_import();
 
-		$seo_title       = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc        = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
-		$robots_noindex  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
-		$robots_nofollow = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
+		$seo_title       = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc        = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$robots_noindex  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-noindex', true );
+		$robots_nofollow = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'meta-robots-nofollow', true );
 
 		$this->assertEquals( 1, $robots_noindex );
 		$this->assertEquals( 0, $robots_nofollow );
@@ -120,8 +121,8 @@ public function test_cleanup() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_cleanup();
 
-		$seo_title = get_post_meta( $post_id, '_su_title', true );
-		$seo_desc  = get_post_meta( $post_id, '_su_description', true );
+		$seo_title = \get_post_meta( $post_id, '_su_title', true );
+		$seo_desc  = \get_post_meta( $post_id, '_su_description', true );
 
 		$this->assertEquals( $seo_title, false );
 		$this->assertEquals( $seo_desc, false );
@@ -147,10 +148,10 @@ private function status( $action, $status ) {
 	 */
 	private function setup_post() {
 		$post_id = $this->factory()->post->create();
-		update_post_meta( $post_id, '_metaseo_metatitle', 'Test title' );
-		update_post_meta( $post_id, '_metaseo_metadesc', 'Test description' );
-		update_post_meta( $post_id, '_metaseo_metafollow', 'follow' );
-		update_post_meta( $post_id, '_metaseo_metaindex', 'noindex' );
+		\update_post_meta( $post_id, '_metaseo_metatitle', 'Test title' );
+		\update_post_meta( $post_id, '_metaseo_metadesc', 'Test description' );
+		\update_post_meta( $post_id, '_metaseo_metafollow', 'follow' );
+		\update_post_meta( $post_id, '_metaseo_metaindex', 'noindex' );
 
 		return $post_id;
 	}
diff --git a/tests/WP/Admin/Import/test-class-import-woothemes-seo.php b/tests/WP/Admin/Import/WooThemes_SEO_Test.php
similarity index 82%
rename from tests/WP/Admin/Import/test-class-import-woothemes-seo.php
rename to tests/WP/Admin/Import/WooThemes_SEO_Test.php
index 31df7981ac8..aaafd1213ee 100644
--- a/tests/WP/Admin/Import/test-class-import-woothemes-seo.php
+++ b/tests/WP/Admin/Import/WooThemes_SEO_Test.php
@@ -1,16 +1,18 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Import\Plugins
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Import;
+
+use WPSEO_Import_Status;
+use WPSEO_Import_WooThemes_SEO;
+use WPSEO_Meta;
+use WPSEO_Options;
+use WPSEO_Plugin_Importers;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Test importing meta data from WooThemes SEO.
  */
-class WPSEO_Import_WooThemes_SEO_Test extends TestCase {
+class WooThemes_SEO_Test extends TestCase {
 
 	/**
 	 * Holds the class instance.
@@ -26,8 +28,8 @@ public function set_up() {
 		parent::set_up();
 
 		// These options need setting as otherwise Woo didn't handle the titles and meta desc and thus we cannot import.
-		update_option( 'seo_woo_wp_title', true );
-		update_option( 'seo_woo_meta_single_desc', 'b' );
+		\update_option( 'seo_woo_wp_title', true );
+		\update_option( 'seo_woo_meta_single_desc', 'b' );
 
 		$this->class_instance = new WPSEO_Import_WooThemes_SEO();
 	}
@@ -47,7 +49,7 @@ public function test_plugin_name() {
 	 * @covers WPSEO_Plugin_Importers::get
 	 */
 	public function test_importer_registered() {
-		$this->assertContains( 'WPSEO_Import_WooThemes_SEO', WPSEO_Plugin_Importers::get() );
+		$this->assertContains( WPSEO_Import_WooThemes_SEO::class, WPSEO_Plugin_Importers::get() );
 	}
 
 	/**
@@ -94,8 +96,8 @@ public function test_import() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_import();
 
-		$seo_title = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
-		$seo_desc  = get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
+		$seo_title = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'title', true );
+		$seo_desc  = \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'metadesc', true );
 
 		$this->assertEquals( $seo_title, 'Test title' );
 		$this->assertEquals( $seo_desc, 'Test description' );
@@ -125,8 +127,8 @@ public function test_cleanup() {
 		$post_id = $this->setup_post();
 		$result  = $this->class_instance->run_cleanup();
 
-		$seo_title = get_post_meta( $post_id, 'seo_title', true );
-		$seo_desc  = get_post_meta( $post_id, 'seo_description', true );
+		$seo_title = \get_post_meta( $post_id, 'seo_title', true );
+		$seo_desc  = \get_post_meta( $post_id, 'seo_description', true );
 
 		$this->assertEquals( false, $seo_title );
 		$this->assertEquals( false, $seo_desc );
@@ -152,8 +154,8 @@ private function status( $action, $status ) {
 	 */
 	private function setup_post() {
 		$post_id = $this->factory()->post->create();
-		update_post_meta( $post_id, 'seo_title', 'Test title' );
-		update_post_meta( $post_id, 'seo_description', 'Test description' );
+		\update_post_meta( $post_id, 'seo_title', 'Test title' );
+		\update_post_meta( $post_id, 'seo_description', 'Test description' );
 
 		return $post_id;
 	}
diff --git a/tests/WP/Admin/test-class-yoast-input-select.php b/tests/WP/Admin/Input_Select_Test.php
similarity index 97%
rename from tests/WP/Admin/test-class-yoast-input-select.php
rename to tests/WP/Admin/Input_Select_Test.php
index 8fa448f7211..ea888f97e34 100644
--- a/tests/WP/Admin/test-class-yoast-input-select.php
+++ b/tests/WP/Admin/Input_Select_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin
- */
+
+namespace Yoast\WP\SEO\Tests\WP\Admin;
 
 use Yoast\WP\SEO\Tests\WP\TestCase;
+use Yoast_Input_Select;
 
 /**
  * Unit Test Class.
  */
-class Yoast_Input_Select_Test extends TestCase {
+class Input_Select_Test extends TestCase {
 
 	/**
 	 * Testing with options.
diff --git a/tests/WP/test-class-wpseo-meta-columns.php b/tests/WP/Admin/Meta_Columns_Test.php
similarity index 98%
rename from tests/WP/test-class-wpseo-meta-columns.php
rename to tests/WP/Admin/Meta_Columns_Test.php
index 006058888ab..10f97396ff7 100644
--- a/tests/WP/test-class-wpseo-meta-columns.php
+++ b/tests/WP/Admin/Meta_Columns_Test.php
@@ -1,17 +1,17 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin;
+
+use WP_User;
+use WPSEO_Meta;
+use WPSEO_Options;
 use Yoast\WP\SEO\Tests\WP\Doubles\Admin\Meta_Columns_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Meta_Columns_Test extends TestCase {
+class Meta_Columns_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
@@ -320,7 +320,7 @@ public function test_column_heading_has_metadesc() {
 	 * @covers WPSEO_Meta_Columns::column_hidden
 	 */
 	public function test_column_hidden_HIDE_COLUMNS() {
-		$user = $this->getMockBuilder( 'WP_User' )
+		$user = $this->getMockBuilder( WP_User::class )
 			->getMock();
 
 		// Option may be filled if the user has not set it.
@@ -343,7 +343,7 @@ public function test_column_hidden_HIDE_COLUMNS() {
 	 */
 	public function test_column_hidden_KEEP_OPTION() {
 		// Option shouldn't be touched if the user has set it already.
-		$user = $this->getMockBuilder( 'WP_User' )
+		$user = $this->getMockBuilder( WP_User::class )
 			->getMock();
 
 		$user->expects( $this->any() )
@@ -366,7 +366,7 @@ public function test_column_hidden_KEEP_OPTION() {
 	 * @covers WPSEO_Meta_Columns::column_hidden
 	 */
 	public function test_column_hidden_UNEXPECTED_VALUE() {
-		$user = $this->getMockBuilder( 'WP_User' )
+		$user = $this->getMockBuilder( WP_User::class )
 			->getMock();
 
 		$user->expects( $this->any() )
diff --git a/tests/WP/test-class-wpseo-metabox.php b/tests/WP/Admin/Metabox/Metabox_Test.php
similarity index 88%
rename from tests/WP/test-class-wpseo-metabox.php
rename to tests/WP/Admin/Metabox/Metabox_Test.php
index f02d7d61c25..072269785f2 100644
--- a/tests/WP/test-class-wpseo-metabox.php
+++ b/tests/WP/Admin/Metabox/Metabox_Test.php
@@ -1,16 +1,19 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Metabox;
+
+use WPSEO_Admin;
+use WPSEO_Admin_Asset_Manager;
+use WPSEO_Meta;
+use WPSEO_Metabox;
+use WPSEO_Options;
+use WPSEO_Post_Type;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Metabox_Test extends TestCase {
+class Metabox_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
@@ -43,7 +46,7 @@ public function test_enqueue_not_firing_on_options_page() {
 		// Call enqueue function.
 		self::$class_instance->enqueue();
 
-		$enqueued = wp_script_is( 'post-edit', 'enqueued' );
+		$enqueued = \wp_script_is( 'post-edit', 'enqueued' );
 		$this->assertFalse( $enqueued );
 	}
 
@@ -62,7 +65,7 @@ public function test_enqueue_firing_on_new_post_page() {
 		// Call enqueue function.
 		self::$class_instance->enqueue();
 
-		$enqueued = wp_script_is( WPSEO_Admin_Asset_Manager::PREFIX . 'post-edit', 'enqueued' );
+		$enqueued = \wp_script_is( WPSEO_Admin_Asset_Manager::PREFIX . 'post-edit', 'enqueued' );
 		$this->assertTrue( $enqueued );
 	}
 
@@ -75,7 +78,7 @@ public function test_add_metabox() {
 		global $wp_meta_boxes;
 
 		$stub = $this
-			->getMockBuilder( 'WPSEO_Metabox' )
+			->getMockBuilder( WPSEO_Metabox::class )
 			->setMethods( [ 'is_metabox_hidden' ] )
 			->getMock();
 
@@ -103,19 +106,20 @@ public function test_add_metabox() {
 	public function test_save_postdata() {
 		// Create and go to post.
 		$post_id = $this->factory->post->create();
-		$this->go_to( get_permalink( $post_id ) );
+		$this->go_to( \get_permalink( $post_id ) );
 
-		$post = get_post( $post_id );
+		$post = \get_post( $post_id );
 
 		$_POST['ID']                       = $post_id;
-		$_POST['yoast_free_metabox_nonce'] = wp_create_nonce( 'yoast_free_metabox' );
+		$_POST['yoast_free_metabox_nonce'] = \wp_create_nonce( 'yoast_free_metabox' );
 
 		// Setup.
+		// phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound -- This has to match the expected name.
 		$GLOBALS['wpseo_admin'] = new WPSEO_Admin();
 
 		// Vars.
-		$meta_fields = apply_filters( 'wpseo_save_metaboxes', [] );
-		$meta_fields = array_merge(
+		$meta_fields = \apply_filters( 'wpseo_save_metaboxes', [] );
+		$meta_fields = \array_merge(
 			$meta_fields,
 			WPSEO_Meta::get_meta_field_defs( 'general', $post->post_type ),
 			WPSEO_Meta::get_meta_field_defs( 'advanced' ),
@@ -141,7 +145,7 @@ public function test_save_postdata() {
 		self::$class_instance->save_postdata( $post->ID );
 
 		// Check if output matches.
-		$custom = get_post_custom( $post->ID );
+		$custom = \get_post_custom( $post->ID );
 		foreach ( $meta_fields as $key => $field ) {
 
 			if ( ! isset( $custom[ WPSEO_Meta::$meta_prefix . $key ][0] ) ) {
@@ -178,7 +182,7 @@ public function test_save_postdata() {
 	public function test_save_postdata_for_separate_fields( $field_name, $field_value, $expected_value, $message ) {
 		// Create and go to post.
 		$post_id = $this->factory->post->create();
-		$this->go_to( get_permalink( $post_id ) );
+		$this->go_to( \get_permalink( $post_id ) );
 
 		$prefixed_field_name = WPSEO_Meta::$form_prefix . $field_name;
 
@@ -186,10 +190,11 @@ public function test_save_postdata_for_separate_fields( $field_name, $field_valu
 			'ID'                       => $post_id,
 			'post_type'                => 'post',
 			$prefixed_field_name       => $field_value,
-			'yoast_free_metabox_nonce' => wp_create_nonce( 'yoast_free_metabox' ),
+			'yoast_free_metabox_nonce' => \wp_create_nonce( 'yoast_free_metabox' ),
 		];
 
 		// Setup.
+		// phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound -- This has to match the expected name.
 		$GLOBALS['wpseo_admin'] = new WPSEO_Admin();
 
 		$disabled_advanced_meta = WPSEO_Options::get( 'disableadvanced_meta' );
diff --git a/tests/WP/Admin/test-class-yoast-network-admin.php b/tests/WP/Admin/Network_Admin_Test.php
similarity index 68%
rename from tests/WP/Admin/test-class-yoast-network-admin.php
rename to tests/WP/Admin/Network_Admin_Test.php
index 91da5594372..fb239869da8 100644
--- a/tests/WP/Admin/test-class-yoast-network-admin.php
+++ b/tests/WP/Admin/Network_Admin_Test.php
@@ -1,16 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin;
+
+use WPDieException;
 use Yoast\WP\SEO\Tests\WP\TestCase;
+use Yoast_Network_Admin;
 
 /**
  * Unit Test Class.
  */
-class Yoast_Network_Admin_Test extends TestCase {
+class Network_Admin_Test extends TestCase {
 
 	/**
 	 * Network administrator user ID.
@@ -28,7 +27,7 @@ class Yoast_Network_Admin_Test extends TestCase {
 	 */
 	public static function wpSetUpBeforeClass( $factory ) {
 		self::$network_administrator = $factory->user->create( [ 'role' => 'administrator' ] );
-		grant_super_admin( self::$network_administrator );
+		\grant_super_admin( self::$network_administrator );
 	}
 
 	/**
@@ -37,7 +36,7 @@ public static function wpSetUpBeforeClass( $factory ) {
 	 * @return void
 	 */
 	public static function wpTearDownAfterClass() {
-		revoke_super_admin( self::$network_administrator );
+		\revoke_super_admin( self::$network_administrator );
 		self::delete_user( self::$network_administrator );
 	}
 
@@ -53,15 +52,15 @@ public function test_get_site_choices() {
 
 		$admin = new Yoast_Network_Admin();
 
-		$site_ids = array_map( 'strval', array_merge( [ get_current_blog_id() ], self::factory()->blog->create_many( 5 ) ) );
+		$site_ids = \array_map( 'strval', \array_merge( [ \get_current_blog_id() ], self::factory()->blog->create_many( 5 ) ) );
 
 		$choices = $admin->get_site_choices();
-		$this->assertSame( $site_ids, array_map( 'strval', array_keys( $choices ) ) );
+		$this->assertSame( $site_ids, \array_map( 'strval', \array_keys( $choices ) ) );
 
-		array_unshift( $site_ids, '-' );
+		\array_unshift( $site_ids, '-' );
 
 		$choices = $admin->get_site_choices( true );
-		$this->assertSame( $site_ids, array_map( 'strval', array_keys( $choices ) ) );
+		$this->assertSame( $site_ids, \array_map( 'strval', \array_keys( $choices ) ) );
 	}
 
 	/**
@@ -77,15 +76,15 @@ public function test_get_site_choices_output() {
 
 		$admin = new Yoast_Network_Admin();
 
-		$site = get_site();
+		$site = \get_site();
 
 		$choices = $admin->get_site_choices();
-		$this->assertSame( $site->id, (int) key( $choices ) );
+		$this->assertSame( $site->id, (int) \key( $choices ) );
 		$this->assertStringStartsWith( (string) $site->id, $choices[ $site->id ] );
 		$this->assertStringContainsString( $site->domain . $site->path, $choices[ $site->id ] );
 
 		$choices = $admin->get_site_choices( false, true );
-		$this->assertSame( $site->id, (int) key( $choices ) );
+		$this->assertSame( $site->id, (int) \key( $choices ) );
 		$this->assertStringStartsWith( (string) $site->id, $choices[ $site->id ] );
 		$this->assertStringContainsString( $site->blogname, $choices[ $site->id ] );
 		$this->assertStringContainsString( $site->domain . $site->path, $choices[ $site->id ] );
@@ -109,10 +108,10 @@ public function test_get_site_states() {
 		];
 
 		$site_id = self::factory()->blog->create();
-		update_blog_details( $site_id, $active_states );
+		\update_blog_details( $site_id, $active_states );
 
-		$site_states = $admin->get_site_states( get_site( $site_id ) );
-		$this->assertSame( array_keys( $active_states ), array_keys( $site_states ) );
+		$site_states = $admin->get_site_states( \get_site( $site_id ) );
+		$this->assertSame( \array_keys( $active_states ), \array_keys( $site_states ) );
 	}
 
 	/**
@@ -123,7 +122,7 @@ public function test_get_site_states() {
 	public function test_handle_update_options_request() {
 		$_POST['network_option_group'] = 'wpseo';
 		$admin                         = $this
-			->getMockBuilder( 'Yoast_Network_Admin' )
+			->getMockBuilder( Yoast_Network_Admin::class )
 			->setMethods( [ 'verify_request', 'terminate_request' ] )
 			->getMock();
 
@@ -146,7 +145,7 @@ public function test_handle_update_options_request() {
 	 */
 	public function test_handle_restore_site_request() {
 		$admin = $this
-			->getMockBuilder( 'Yoast_Network_Admin' )
+			->getMockBuilder( Yoast_Network_Admin::class )
 			->setMethods( [ 'verify_request', 'terminate_request' ] )
 			->getMock();
 
@@ -172,14 +171,14 @@ public function test_settings_fields() {
 
 		$group = 'yst_ms_group';
 
-		ob_start();
+		\ob_start();
 		$admin->settings_fields( $group );
-		$output = ob_get_clean();
+		$output = \ob_get_clean();
 
-		$this->assertTrue( (bool) strpos( $output, 'name="network_option_group" value="' . $group . '"' ) );
-		$this->assertTrue( (bool) strpos( $output, 'name="action" value="' . Yoast_Network_Admin::UPDATE_OPTIONS_ACTION . '"' ) );
-		$this->assertTrue( (bool) preg_match( '/name="_wpnonce" value="([a-z0-9]+)"/', $output, $matches ) );
-		$this->assertTrue( (bool) wp_verify_nonce( $matches[1], $group . '-network-options' ) );
+		$this->assertTrue( (bool) \strpos( $output, 'name="network_option_group" value="' . $group . '"' ) );
+		$this->assertTrue( (bool) \strpos( $output, 'name="action" value="' . Yoast_Network_Admin::UPDATE_OPTIONS_ACTION . '"' ) );
+		$this->assertTrue( (bool) \preg_match( '/name="_wpnonce" value="([a-z0-9]+)"/', $output, $matches ) );
+		$this->assertTrue( (bool) \wp_verify_nonce( $matches[1], $group . '-network-options' ) );
 	}
 
 	/**
@@ -188,7 +187,7 @@ public function test_settings_fields() {
 	 * @covers Yoast_Network_Admin::register_hooks
 	 */
 	public function test_register_hooks() {
-		$admin = $this->getMockBuilder( 'Yoast_Network_Admin' )
+		$admin = $this->getMockBuilder( Yoast_Network_Admin::class )
 			->setMethods( [ 'meets_requirements' ] )
 			->getMock();
 
@@ -198,8 +197,8 @@ public function test_register_hooks() {
 			->will( $this->returnValue( true ) );
 
 		$admin->register_hooks();
-		$this->assertIsInt( has_action( 'admin_action_' . Yoast_Network_Admin::UPDATE_OPTIONS_ACTION, [ $admin, 'handle_update_options_request' ] ) );
-		$this->assertIsInt( has_action( 'admin_action_' . Yoast_Network_Admin::RESTORE_SITE_ACTION, [ $admin, 'handle_restore_site_request' ] ) );
+		$this->assertIsInt( \has_action( 'admin_action_' . Yoast_Network_Admin::UPDATE_OPTIONS_ACTION, [ $admin, 'handle_update_options_request' ] ) );
+		$this->assertIsInt( \has_action( 'admin_action_' . Yoast_Network_Admin::RESTORE_SITE_ACTION, [ $admin, 'handle_restore_site_request' ] ) );
 	}
 
 	/**
@@ -211,8 +210,8 @@ public function test_register_ajax_hooks() {
 		$admin = new Yoast_Network_Admin();
 
 		$admin->register_ajax_hooks();
-		$this->assertIsInt( has_action( 'wp_ajax_' . Yoast_Network_Admin::UPDATE_OPTIONS_ACTION, [ $admin, 'handle_update_options_request' ] ) );
-		$this->assertIsInt( has_action( 'wp_ajax_' . Yoast_Network_Admin::RESTORE_SITE_ACTION, [ $admin, 'handle_restore_site_request' ] ) );
+		$this->assertIsInt( \has_action( 'wp_ajax_' . Yoast_Network_Admin::UPDATE_OPTIONS_ACTION, [ $admin, 'handle_update_options_request' ] ) );
+		$this->assertIsInt( \has_action( 'wp_ajax_' . Yoast_Network_Admin::RESTORE_SITE_ACTION, [ $admin, 'handle_restore_site_request' ] ) );
 	}
 
 	/**
@@ -235,12 +234,12 @@ public function test_meets_requirements() {
 	public function test_verify_request_with_invalid_nonce() {
 		$admin = new Yoast_Network_Admin();
 
-		$_REQUEST['_wp_http_referer'] = admin_url();
+		$_REQUEST['_wp_http_referer'] = \admin_url();
 		$_REQUEST['_wpnonce']         = '';
 
 		$expected_message = 'The link you followed has expired.';
 
-		$this->expectException( 'WPDieException' );
+		$this->expectException( WPDieException::class );
 		$this->expectExceptionMessage( $expected_message );
 
 		$admin->verify_request( 'my_action' );
@@ -254,10 +253,10 @@ public function test_verify_request_with_invalid_nonce() {
 	public function test_verify_request_with_valid_nonce_but_lacking_caps() {
 		$admin = new Yoast_Network_Admin();
 
-		$_REQUEST['_wp_http_referer'] = admin_url();
-		$_REQUEST['_wpnonce']         = wp_create_nonce( 'my_action' );
+		$_REQUEST['_wp_http_referer'] = \admin_url();
+		$_REQUEST['_wpnonce']         = \wp_create_nonce( 'my_action' );
 
-		$this->expectException( 'WPDieException' );
+		$this->expectException( WPDieException::class );
 		$this->expectExceptionMessage( 'You are not allowed to perform this action.' );
 
 		$admin->verify_request( 'my_action' );
@@ -271,11 +270,11 @@ public function test_verify_request_with_valid_nonce_but_lacking_caps() {
 	public function test_verify_request_with_valid_nonce_and_caps() {
 		$admin = new Yoast_Network_Admin();
 
-		wp_set_current_user( self::$network_administrator );
-		wp_get_current_user()->add_cap( 'wpseo_manage_network_options' );
+		\wp_set_current_user( self::$network_administrator );
+		\wp_get_current_user()->add_cap( 'wpseo_manage_network_options' );
 
-		$_REQUEST['_wp_http_referer'] = admin_url();
-		$_REQUEST['_wpnonce']         = wp_create_nonce( 'my_action' );
+		$_REQUEST['_wp_http_referer'] = \admin_url();
+		$_REQUEST['_wpnonce']         = \wp_create_nonce( 'my_action' );
 
 		$e = null;
 		try {
@@ -295,12 +294,12 @@ public function test_verify_request_with_valid_nonce_and_caps() {
 	public function test_verify_request_ajax_with_invalid_nonce() {
 		$admin = new Yoast_Network_Admin();
 
-		add_filter( 'wp_doing_ajax', '__return_true' );
-		add_filter( 'wp_die_ajax_handler', [ $this, 'get_wp_die_handler' ] );
+		\add_filter( 'wp_doing_ajax', '__return_true' );
+		\add_filter( 'wp_die_ajax_handler', [ $this, 'get_wp_die_handler' ] );
 
 		$_REQUEST['_wpnonce'] = '';
 
-		$this->expectException( 'WPDieException' );
+		$this->expectException( WPDieException::class );
 		$this->expectExceptionMessage( '-1' );
 
 		$admin->verify_request( 'my_action' );
@@ -314,12 +313,12 @@ public function test_verify_request_ajax_with_invalid_nonce() {
 	public function test_verify_request_ajax_with_valid_nonce_but_lacking_caps() {
 		$admin = new Yoast_Network_Admin();
 
-		add_filter( 'wp_doing_ajax', '__return_true' );
-		add_filter( 'wp_die_ajax_handler', [ $this, 'get_wp_die_handler' ] );
+		\add_filter( 'wp_doing_ajax', '__return_true' );
+		\add_filter( 'wp_die_ajax_handler', [ $this, 'get_wp_die_handler' ] );
 
-		$_REQUEST['_wpnonce'] = wp_create_nonce( 'my_action' );
+		$_REQUEST['_wpnonce'] = \wp_create_nonce( 'my_action' );
 
-		$this->expectException( 'WPDieException' );
+		$this->expectException( WPDieException::class );
 		$this->expectExceptionMessage( '-1' );
 
 		$admin->verify_request( 'my_action' );
@@ -333,13 +332,13 @@ public function test_verify_request_ajax_with_valid_nonce_but_lacking_caps() {
 	public function test_verify_request_ajax_with_valid_nonce_and_caps() {
 		$admin = new Yoast_Network_Admin();
 
-		add_filter( 'wp_doing_ajax', '__return_true' );
-		add_filter( 'wp_die_ajax_handler', [ $this, 'get_wp_die_handler' ] );
+		\add_filter( 'wp_doing_ajax', '__return_true' );
+		\add_filter( 'wp_die_ajax_handler', [ $this, 'get_wp_die_handler' ] );
 
-		wp_set_current_user( self::$network_administrator );
-		wp_get_current_user()->add_cap( 'wpseo_manage_network_options' );
+		\wp_set_current_user( self::$network_administrator );
+		\wp_get_current_user()->add_cap( 'wpseo_manage_network_options' );
 
-		$_REQUEST['_wpnonce'] = wp_create_nonce( 'my_action' );
+		$_REQUEST['_wpnonce'] = \wp_create_nonce( 'my_action' );
 
 		$e = null;
 		try {
@@ -358,7 +357,7 @@ public function test_verify_request_ajax_with_valid_nonce_and_caps() {
 	 */
 	public function test_terminate_request() {
 		$admin = $this
-			->getMockBuilder( 'Yoast_Network_Admin' )
+			->getMockBuilder( Yoast_Network_Admin::class )
 			->setMethods( [ 'persist_settings_errors', 'redirect_back' ] )
 			->getMock();
 
@@ -384,12 +383,12 @@ public function test_terminate_request() {
 	public function test_terminate_request_ajax() {
 		$admin = new Yoast_Network_Admin();
 
-		add_filter( 'wp_doing_ajax', '__return_true' );
-		add_filter( 'wp_die_ajax_handler', [ $this, 'get_wp_die_handler' ] );
+		\add_filter( 'wp_doing_ajax', '__return_true' );
+		\add_filter( 'wp_die_ajax_handler', [ $this, 'get_wp_die_handler' ] );
 
-		$_REQUEST['_wpnonce'] = wp_create_nonce( 'my_action' );
+		$_REQUEST['_wpnonce'] = \wp_create_nonce( 'my_action' );
 
-		$this->expectException( 'WPDieException' );
+		$this->expectException( WPDieException::class );
 		$this->expectExceptionMessage( '' );
 
 		$this->expectOutputContains( 'success' );
@@ -397,7 +396,7 @@ public function test_terminate_request_ajax() {
 		try {
 			$admin->terminate_request();
 		} catch ( WPDieException $e ) {
-			$output_decoded = json_decode( $this->getActualOutput(), true );
+			$output_decoded = \json_decode( $this->getActualOutput(), true );
 			$this->assertArrayHasKey( 'success', $output_decoded );
 			throw $e;
 		}
diff --git a/tests/WP/Admin/test-class-yoast-network-settings-api.php b/tests/WP/Admin/Network_Settings_API_Test.php
similarity index 84%
rename from tests/WP/Admin/test-class-yoast-network-settings-api.php
rename to tests/WP/Admin/Network_Settings_API_Test.php
index 12307eb467e..2f6e99d995d 100644
--- a/tests/WP/Admin/test-class-yoast-network-settings-api.php
+++ b/tests/WP/Admin/Network_Settings_API_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin
- */
+
+namespace Yoast\WP\SEO\Tests\WP\Admin;
 
 use Yoast\WP\SEO\Tests\WP\TestCase;
+use Yoast_Network_Settings_API;
 
 /**
  * Unit Test Class.
  */
-class Yoast_Network_Settings_API_Test extends TestCase {
+class Network_Settings_API_Test extends TestCase {
 
 	/**
 	 * Tests registering a setting.
@@ -26,8 +24,8 @@ public function test_register_setting() {
 		];
 		$api->register_setting( 'yst_ms_group', 'yst_ms_option', $setting_args );
 
-		$this->assertIsInt( has_filter( 'sanitize_option_yst_ms_option', [ $api, 'filter_sanitize_option' ] ) );
-		$this->assertIsInt( has_filter( 'default_site_option_yst_ms_option', [ $api, 'filter_default_option' ] ) );
+		$this->assertIsInt( \has_filter( 'sanitize_option_yst_ms_option', [ $api, 'filter_sanitize_option' ] ) );
+		$this->assertIsInt( \has_filter( 'default_site_option_yst_ms_option', [ $api, 'filter_default_option' ] ) );
 	}
 
 	/**
@@ -46,7 +44,7 @@ public function test_get_registered_settings() {
 		$api = new Yoast_Network_Settings_API();
 		$api->register_setting( $group, $name, $args );
 
-		$args     = array_merge( [ 'group' => $group ], $args );
+		$args     = \array_merge( [ 'group' => $group ], $args );
 		$expected = [ $name => $args ];
 
 		$this->assertSame( $expected, $api->get_registered_settings() );
@@ -113,7 +111,7 @@ public function test_filter_default_option() {
 	 * @covers Yoast_Network_Settings_API::get
 	 */
 	public function test_get() {
-		$this->assertInstanceOf( 'Yoast_Network_Settings_API', Yoast_Network_Settings_API::get() );
+		$this->assertInstanceOf( Yoast_Network_Settings_API::class, Yoast_Network_Settings_API::get() );
 	}
 
 	/**
@@ -124,6 +122,6 @@ public function test_get() {
 	public function test_meets_requirements() {
 		$api = new Yoast_Network_Settings_API();
 
-		$this->assertSame( is_multisite(), $api->meets_requirements() );
+		$this->assertSame( \is_multisite(), $api->meets_requirements() );
 	}
 }
diff --git a/tests/WP/Admin/test-class-option-tab.php b/tests/WP/Admin/Option_Tab_Test.php
similarity index 94%
rename from tests/WP/Admin/test-class-option-tab.php
rename to tests/WP/Admin/Option_Tab_Test.php
index 91da93f046d..1b9f2a40aea 100644
--- a/tests/WP/Admin/test-class-option-tab.php
+++ b/tests/WP/Admin/Option_Tab_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin;
+
+use WPSEO_Option_Tab;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Option_Tab_Test extends TestCase {
+class Option_Tab_Test extends TestCase {
 
 	/**
 	 * Tests that the name is returned properly.
diff --git a/tests/WP/Admin/test-class-option-tabs.php b/tests/WP/Admin/Option_Tabs_Test.php
similarity index 96%
rename from tests/WP/Admin/test-class-option-tabs.php
rename to tests/WP/Admin/Option_Tabs_Test.php
index 4a3c0c67346..f259f16c222 100644
--- a/tests/WP/Admin/test-class-option-tabs.php
+++ b/tests/WP/Admin/Option_Tabs_Test.php
@@ -1,16 +1,16 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin;
+
+use WPSEO_Option_Tab;
+use WPSEO_Option_Tabs;
 use Yoast\WP\SEO\Tests\WP\TestCase;
+use Yoast_Form;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Option_Tabs_Test extends TestCase {
+class Option_Tabs_Test extends TestCase {
 
 	/**
 	 * Tests the retrieval of the base.
diff --git a/tests/WP/Admin/test-class-plugin-availability.php b/tests/WP/Admin/Plugin_Availability_Test.php
similarity index 96%
rename from tests/WP/Admin/test-class-plugin-availability.php
rename to tests/WP/Admin/Plugin_Availability_Test.php
index dbf8505a892..a78f959eeaf 100644
--- a/tests/WP/Admin/test-class-plugin-availability.php
+++ b/tests/WP/Admin/Plugin_Availability_Test.php
@@ -1,9 +1,6 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin
- */
+
+namespace Yoast\WP\SEO\Tests\WP\Admin;
 
 use Yoast\WP\SEO\Tests\WP\Doubles\Admin\Plugin_Availability_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
@@ -13,7 +10,7 @@
  *
  * @coversDefaultClass WPSEO_Plugin_Availability
  */
-class WPSEO_Plugin_Availability_Test extends TestCase {
+class Plugin_Availability_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
diff --git a/tests/WP/Admin/test-class-plugin-suggestions.php b/tests/WP/Admin/Plugin_Suggestions_Test.php
similarity index 93%
rename from tests/WP/Admin/test-class-plugin-suggestions.php
rename to tests/WP/Admin/Plugin_Suggestions_Test.php
index c387ebd5a27..b02ca54d893 100644
--- a/tests/WP/Admin/test-class-plugin-suggestions.php
+++ b/tests/WP/Admin/Plugin_Suggestions_Test.php
@@ -1,9 +1,6 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin
- */
+
+namespace Yoast\WP\SEO\Tests\WP\Admin;
 
 use Yoast\WP\SEO\Tests\WP\Doubles\Admin\Plugin_Availability_Double;
 use Yoast\WP\SEO\Tests\WP\Doubles\Admin\Suggested_Plugins_Double;
@@ -15,7 +12,7 @@
  *
  * @coversDefaultClass WPSEO_Suggested_Plugins
  */
-class WPSEO_Plugin_Suggestions_Test extends TestCase {
+class Plugin_Suggestions_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
diff --git a/tests/WP/test-class-primary-term-admin.php b/tests/WP/Admin/Primary_Term_Admin_Test.php
similarity index 86%
rename from tests/WP/test-class-primary-term-admin.php
rename to tests/WP/Admin/Primary_Term_Admin_Test.php
index 39e10399e3b..e674c4b28f9 100644
--- a/tests/WP/test-class-primary-term-admin.php
+++ b/tests/WP/Admin/Primary_Term_Admin_Test.php
@@ -1,16 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin;
+
+use WPSEO_Admin_Asset_Manager;
+use WPSEO_Primary_Term_Admin;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Primary_Term_Admin_Test extends TestCase {
+class Primary_Term_Admin_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
@@ -25,7 +24,7 @@ class WPSEO_Primary_Term_Admin_Test extends TestCase {
 	public function set_up() {
 		parent::set_up();
 
-		$this->class_instance = $this->getMockBuilder( 'WPSEO_Primary_Term_Admin' )
+		$this->class_instance = $this->getMockBuilder( WPSEO_Primary_Term_Admin::class )
 			->setMethods( [ 'get_primary_term_taxonomies', 'include_js_templates', 'save_primary_term', 'get_primary_term' ] )
 			->getMock();
 	}
@@ -80,7 +79,7 @@ public function test_wp_footer_INCLUDE_WITH_taxonomies() {
 	public function test_enqueue_assets_EMPTY_taxonomies_DO_NOT_enqueue_scripts() {
 		$this->class_instance->enqueue_assets();
 
-		$this->assertFalse( wp_style_is( 'wpseo-primary-category', 'registered' ) );
+		$this->assertFalse( \wp_style_is( 'wpseo-primary-category', 'registered' ) );
 	}
 
 	/**
@@ -97,7 +96,7 @@ public function test_enqueue_assets_DO_NOT_enqueue_scripts() {
 
 		$this->class_instance->enqueue_assets();
 
-		$this->assertFalse( wp_style_is( 'wpseo-primary-category', 'registered' ) );
+		$this->assertFalse( \wp_style_is( 'wpseo-primary-category', 'registered' ) );
 	}
 
 	/**
@@ -132,6 +131,6 @@ public function test_enqueue_assets_WITH_taxonomies_DO_enqueue_scripts() {
 
 		$this->class_instance->enqueue_assets();
 
-		$this->assertTrue( wp_style_is( WPSEO_Admin_Asset_Manager::PREFIX . 'primary-category', 'registered' ) );
+		$this->assertTrue( \wp_style_is( WPSEO_Admin_Asset_Manager::PREFIX . 'primary-category', 'registered' ) );
 	}
 }
diff --git a/tests/WP/Admin/test-class-admin-recommended-replace-vars.php b/tests/WP/Admin/Recommended_Replace_Vars_Test.php
similarity index 94%
rename from tests/WP/Admin/test-class-admin-recommended-replace-vars.php
rename to tests/WP/Admin/Recommended_Replace_Vars_Test.php
index f8c811e71a2..83d1b1f2486 100644
--- a/tests/WP/Admin/test-class-admin-recommended-replace-vars.php
+++ b/tests/WP/Admin/Recommended_Replace_Vars_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin;
+
+use WPSEO_Admin_Recommended_Replace_Vars;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Admin_Recommended_Replace_Vars_Test extends TestCase {
+class Recommended_Replace_Vars_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
@@ -26,7 +24,7 @@ public function set_up() {
 		parent::set_up();
 
 		$this->class_instance = new WPSEO_Admin_Recommended_Replace_Vars();
-		add_filter( 'wpseo_recommended_replace_vars', [ $this, 'filter_recommended_replacevars' ] );
+		\add_filter( 'wpseo_recommended_replace_vars', [ $this, 'filter_recommended_replacevars' ] );
 	}
 
 	/**
@@ -73,20 +71,20 @@ public function test_determine_for_post_without_a_wp_post_instance() {
 	 */
 	public function test_determine_for_post_with_a_homepage() {
 		// Backup the current values for these options.
-		$show_on_front = get_option( 'show_on_front' );
-		$page_on_front = get_option( 'page_on_front' );
+		$show_on_front = \get_option( 'show_on_front' );
+		$page_on_front = \get_option( 'page_on_front' );
 
 		$post = $this->create_and_get_with_post_type( 'page' );
 
 		// Overwrite the options used in the is_homepage function.
-		update_option( 'show_on_front', 'page' );
-		update_option( 'page_on_front', $post->ID );
+		\update_option( 'show_on_front', 'page' );
+		\update_option( 'page_on_front', $post->ID );
 
 		$this->assertEquals( 'homepage', $this->class_instance->determine_for_post( $post ) );
 
 		// Revert the options their original values.
-		update_option( 'show_on_front', $show_on_front );
-		update_option( 'page_on_front', $page_on_front );
+		\update_option( 'show_on_front', $show_on_front );
+		\update_option( 'page_on_front', $page_on_front );
 	}
 
 	/**
diff --git a/tests/WP/Admin/test-class-schema-person-upgrade-notification.php b/tests/WP/Admin/Schema_Person_Upgrade_Notification_Test.php
similarity index 77%
rename from tests/WP/Admin/test-class-schema-person-upgrade-notification.php
rename to tests/WP/Admin/Schema_Person_Upgrade_Notification_Test.php
index fcd4275cf00..c5fb31e6ce7 100644
--- a/tests/WP/Admin/test-class-schema-person-upgrade-notification.php
+++ b/tests/WP/Admin/Schema_Person_Upgrade_Notification_Test.php
@@ -1,10 +1,9 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin;
+
+use WPSEO_Options;
+use WPSEO_Schema_Person_Upgrade_Notification;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
@@ -12,7 +11,7 @@
  *
  * @group Person_Schema
  */
-class WPSEO_Schema_Person_Upgrade_Notification_Test extends TestCase {
+class Schema_Person_Upgrade_Notification_Test extends TestCase {
 
 	/**
 	 * Remove the notification when Person is not selected.
@@ -20,7 +19,7 @@ class WPSEO_Schema_Person_Upgrade_Notification_Test extends TestCase {
 	 * @covers WPSEO_Schema_Person_Upgrade_Notification::handle_notification
 	 */
 	public function test_remove_notification_not_person() {
-		$instance = $this->getMockBuilder( 'WPSEO_Schema_Person_Upgrade_Notification' )
+		$instance = $this->getMockBuilder( WPSEO_Schema_Person_Upgrade_Notification::class )
 			->setMethods( [ 'remove_notification' ] )
 			->getMock();
 
@@ -37,7 +36,7 @@ public function test_remove_notification_not_person() {
 	 * @covers WPSEO_Schema_Person_Upgrade_Notification::handle_notification
 	 */
 	public function test_remove_notification_user_id_set() {
-		$instance = $this->getMockBuilder( 'WPSEO_Schema_Person_Upgrade_Notification' )
+		$instance = $this->getMockBuilder( WPSEO_Schema_Person_Upgrade_Notification::class )
 			->setMethods( [ 'remove_notification' ] )
 			->getMock();
 
@@ -55,7 +54,7 @@ public function test_remove_notification_user_id_set() {
 	 * @covers WPSEO_Schema_Person_Upgrade_Notification::handle_notification
 	 */
 	public function test_add_notification() {
-		$instance = $this->getMockBuilder( 'WPSEO_Schema_Person_Upgrade_Notification' )
+		$instance = $this->getMockBuilder( WPSEO_Schema_Person_Upgrade_Notification::class )
 			->setMethods( [ 'add_notification' ] )
 			->getMock();
 
diff --git a/tests/WP/Admin/Services/test-class-file-size.php b/tests/WP/Admin/Services/File_Size_Service_Test.php
similarity index 90%
rename from tests/WP/Admin/Services/test-class-file-size.php
rename to tests/WP/Admin/Services/File_Size_Service_Test.php
index 1bd0183bf2a..b6920a920c3 100644
--- a/tests/WP/Admin/Services/test-class-file-size.php
+++ b/tests/WP/Admin/Services/File_Size_Service_Test.php
@@ -1,16 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Services;
+
+use WP_REST_Request;
+use WPSEO_File_Size_Service;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_File_Size_Service_Test extends TestCase {
+class File_Size_Service_Test extends TestCase {
 
 	/**
 	 * Tests the retrieval of the file size for external hosted file.
@@ -22,7 +21,7 @@ public function test_get_for_externally_hosted_file() {
 		$request->set_param( 'url', 'external.file' );
 
 		$instance = $this
-			->getMockBuilder( 'WPSEO_File_Size_Service' )
+			->getMockBuilder( WPSEO_File_Size_Service::class )
 			->setMethods( [ 'is_externally_hosted' ] )
 			->getMock();
 
@@ -44,7 +43,7 @@ public function test_get_for_externally_hosted_file() {
 	 */
 	public function test_get_with_unknown_failure() {
 		$instance = $this
-			->getMockBuilder( 'WPSEO_File_Size_Service' )
+			->getMockBuilder( WPSEO_File_Size_Service::class )
 			->setMethods( [ 'get_file_url', 'calculate_file_size' ] )
 			->getMock();
 
@@ -71,7 +70,7 @@ public function test_get_with_unknown_failure() {
 	 */
 	public function test_get_on_success() {
 		$instance = $this
-			->getMockBuilder( 'WPSEO_File_Size_Service' )
+			->getMockBuilder( WPSEO_File_Size_Service::class )
 			->setMethods( [ 'get_file_url', 'get_file_size' ] )
 			->getMock();
 
@@ -102,7 +101,7 @@ public function test_get_file_url_for_externally_hosted_file() {
 		$request->set_param( 'url', 'https://extern.al/external.file' );
 
 		$instance = $this
-			->getMockBuilder( 'WPSEO_File_Size_Service' )
+			->getMockBuilder( WPSEO_File_Size_Service::class )
 			->setMethods( [ 'is_externally_hosted' ] )
 			->getMock();
 
@@ -128,7 +127,7 @@ public function test_get_file_url_for_local_file() {
 		$request->set_param( 'url', 'local.file' );
 
 		$instance = $this
-			->getMockBuilder( 'WPSEO_File_Size_Service' )
+			->getMockBuilder( WPSEO_File_Size_Service::class )
 			->setMethods( [ 'is_externally_hosted', 'get_file_size' ] )
 			->getMock();
 
diff --git a/tests/WP/Admin/Watchers/test-class-indexable-post-watcher.php b/tests/WP/Admin/Watchers/Indexable_Post_Watcher_Test.php
similarity index 91%
rename from tests/WP/Admin/Watchers/test-class-indexable-post-watcher.php
rename to tests/WP/Admin/Watchers/Indexable_Post_Watcher_Test.php
index 88f486dcd70..6e87ed0b1d7 100644
--- a/tests/WP/Admin/Watchers/test-class-indexable-post-watcher.php
+++ b/tests/WP/Admin/Watchers/Indexable_Post_Watcher_Test.php
@@ -1,10 +1,8 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Watchers
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Watchers;
+
+use WP_Post;
 use Yoast\WP\Lib\Model;
 use Yoast\WP\SEO\Models\Indexable;
 use Yoast\WP\SEO\Models\Indexable_Hierarchy;
@@ -50,7 +48,7 @@ public function test_create_post() {
 	public function test_delete_post() {
 		$post = $this->factory()->post->create_and_get();
 
-		wp_delete_post( $post->ID, true );
+		\wp_delete_post( $post->ID, true );
 
 		$indexables = $this->get_indexables_for( $post );
 
@@ -73,7 +71,7 @@ public function test_delete_post_indexable_removed_after_creation() {
 
 		$this->assertCount( 0, $indexables );
 
-		wp_delete_post( $post->ID, true );
+		\wp_delete_post( $post->ID, true );
 
 		$this->assertCount( 0, $indexables );
 	}
@@ -99,8 +97,8 @@ public function test_create_post_with_hierarchy() {
 			]
 		);
 
-		$parent_indexable = current( $this->get_indexables_for( $parent ) );
-		$child_indexable  = current( $this->get_indexables_for( $child ) );
+		$parent_indexable = \current( $this->get_indexables_for( $parent ) );
+		$child_indexable  = \current( $this->get_indexables_for( $child ) );
 
 		$parent_hierarchy = $this->get_hierarchy_for( $parent_indexable );
 		$child_hierarchy  = $this->get_hierarchy_for( $child_indexable );
@@ -129,10 +127,10 @@ public function test_delete_post_with_hierarchy() {
 			]
 		);
 
-		$parent_indexable = current( $this->get_indexables_for( $parent ) );
-		$child_indexable  = current( $this->get_indexables_for( $child ) );
+		$parent_indexable = \current( $this->get_indexables_for( $parent ) );
+		$child_indexable  = \current( $this->get_indexables_for( $child ) );
 
-		wp_delete_post( $parent->ID, true );
+		\wp_delete_post( $parent->ID, true );
 
 		$parent_hierarchy = $this->get_hierarchy_for( $parent_indexable );
 		$child_hierarchy  = $this->get_hierarchy_for( $child_indexable );
diff --git a/tests/WP/Admin/Watchers/test-class-slug-change-watcher.php b/tests/WP/Admin/Watchers/Slug_Change_Watcher_Test.php
similarity index 78%
rename from tests/WP/Admin/Watchers/test-class-slug-change-watcher.php
rename to tests/WP/Admin/Watchers/Slug_Change_Watcher_Test.php
index e4f24c9cef6..62ef43d410a 100644
--- a/tests/WP/Admin/Watchers/test-class-slug-change-watcher.php
+++ b/tests/WP/Admin/Watchers/Slug_Change_Watcher_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin\Watchers
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin\Watchers;
+
+use WPSEO_Slug_Change_Watcher;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Slug_Change_Watcher_Test extends TestCase {
+class Slug_Change_Watcher_Test extends TestCase {
 
 	/**
 	 * Post ID.
@@ -60,10 +58,10 @@ public static function wpSetUpBeforeClass( $factory ) {
 	 * @return void
 	 */
 	public static function wpTearDownAfterClass() {
-		wp_delete_post( self::$post_id, true );
-		wp_delete_post( self::$nav_menu_item_id, true );
-		wp_delete_term( self::$category_id, 'category' );
-		wp_delete_term( self::$nav_menu_id, 'nav_menu' );
+		\wp_delete_post( self::$post_id, true );
+		\wp_delete_post( self::$nav_menu_item_id, true );
+		\wp_delete_term( self::$category_id, 'category' );
+		\wp_delete_term( self::$nav_menu_id, 'nav_menu' );
 	}
 
 	/**
@@ -73,7 +71,7 @@ public static function wpTearDownAfterClass() {
 	 */
 	public function test_detect_post_trash() {
 		$instance = $this
-			->getMockBuilder( 'WPSEO_Slug_Change_Watcher' )
+			->getMockBuilder( WPSEO_Slug_Change_Watcher::class )
 			->setMethods( [ 'add_notification' ] )
 			->getMock();
 
@@ -83,7 +81,7 @@ public function test_detect_post_trash() {
 
 		$instance->register_hooks();
 
-		wp_trash_post( self::$post_id );
+		\wp_trash_post( self::$post_id );
 	}
 
 	/**
@@ -98,10 +96,10 @@ public function test_detect_post_trash_no_visible_post_status() {
 			'ID'          => self::$post_id,
 			'post_status' => 'draft',
 		];
-		wp_update_post( $post_args );
+		\wp_update_post( $post_args );
 
 		$instance = $this
-			->getMockBuilder( 'WPSEO_Slug_Change_Watcher' )
+			->getMockBuilder( WPSEO_Slug_Change_Watcher::class )
 			->setMethods( [ 'add_notification' ] )
 			->getMock();
 
@@ -111,7 +109,7 @@ public function test_detect_post_trash_no_visible_post_status() {
 
 		$instance->register_hooks();
 
-		wp_trash_post( self::$post_id );
+		\wp_trash_post( self::$post_id );
 	}
 
 	/**
@@ -121,7 +119,7 @@ public function test_detect_post_trash_no_visible_post_status() {
 	 */
 	public function test_detect_post_delete() {
 		$instance = $this
-			->getMockBuilder( 'WPSEO_Slug_Change_Watcher' )
+			->getMockBuilder( WPSEO_Slug_Change_Watcher::class )
 			->setMethods( [ 'add_notification' ] )
 			->getMock();
 
@@ -131,7 +129,7 @@ public function test_detect_post_delete() {
 
 		$instance->register_hooks();
 
-		wp_delete_post( self::$post_id );
+		\wp_delete_post( self::$post_id );
 	}
 
 	/**
@@ -141,7 +139,7 @@ public function test_detect_post_delete() {
 	 */
 	public function test_detect_post_delete_menu_item() {
 		$instance = $this
-			->getMockBuilder( 'WPSEO_Slug_Change_Watcher' )
+			->getMockBuilder( WPSEO_Slug_Change_Watcher::class )
 			->setMethods( [ 'add_notification' ] )
 			->getMock();
 
@@ -151,7 +149,7 @@ public function test_detect_post_delete_menu_item() {
 
 		$instance->register_hooks();
 
-		wp_delete_post( self::$nav_menu_item_id );
+		\wp_delete_post( self::$nav_menu_item_id );
 	}
 
 	/**
@@ -165,10 +163,10 @@ public function test_detect_post_delete_trashed_post() {
 			'ID'          => self::$post_id,
 			'post_status' => 'trash',
 		];
-		wp_update_post( $post_args );
+		\wp_update_post( $post_args );
 
 		$instance = $this
-			->getMockBuilder( 'WPSEO_Slug_Change_Watcher' )
+			->getMockBuilder( WPSEO_Slug_Change_Watcher::class )
 			->setMethods( [ 'add_notification' ] )
 			->getMock();
 
@@ -178,7 +176,7 @@ public function test_detect_post_delete_trashed_post() {
 
 		$instance->register_hooks();
 
-		wp_delete_post( self::$post_id );
+		\wp_delete_post( self::$post_id );
 	}
 
 	/**
@@ -187,10 +185,10 @@ public function test_detect_post_delete_trashed_post() {
 	 * @covers WPSEO_Slug_Change_Watcher::detect_post_delete
 	 */
 	public function test_detect_post_delete_revision() {
-		$revision_id = wp_save_post_revision( self::$post_id );
+		$revision_id = \wp_save_post_revision( self::$post_id );
 
 		$instance = $this
-			->getMockBuilder( 'WPSEO_Slug_Change_Watcher' )
+			->getMockBuilder( WPSEO_Slug_Change_Watcher::class )
 			->setMethods( [ 'add_notification' ] )
 			->getMock();
 
@@ -200,7 +198,7 @@ public function test_detect_post_delete_revision() {
 
 		$instance->register_hooks();
 
-		wp_delete_post( $revision_id );
+		\wp_delete_post( $revision_id );
 	}
 
 	/**
@@ -215,10 +213,10 @@ public function test_detect_post_delete_when_not_visible() {
 			'ID'          => self::$post_id,
 			'post_status' => 'pending',
 		];
-		wp_update_post( $post_args );
+		\wp_update_post( $post_args );
 
 		$instance = $this
-			->getMockBuilder( 'WPSEO_Slug_Change_Watcher' )
+			->getMockBuilder( WPSEO_Slug_Change_Watcher::class )
 			->setMethods( [ 'add_notification' ] )
 			->getMock();
 
@@ -228,7 +226,7 @@ public function test_detect_post_delete_when_not_visible() {
 
 		$instance->register_hooks();
 
-		wp_delete_post( self::$post_id );
+		\wp_delete_post( self::$post_id );
 	}
 
 	/**
@@ -238,7 +236,7 @@ public function test_detect_post_delete_when_not_visible() {
 	 */
 	public function test_detect_term_delete() {
 		$instance = $this
-			->getMockBuilder( 'WPSEO_Slug_Change_Watcher' )
+			->getMockBuilder( WPSEO_Slug_Change_Watcher::class )
 			->setMethods( [ 'add_notification' ] )
 			->getMock();
 
@@ -248,7 +246,7 @@ public function test_detect_term_delete() {
 
 		$instance->register_hooks();
 
-		wp_delete_term( self::$category_id, 'category' );
+		\wp_delete_term( self::$category_id, 'category' );
 	}
 
 	/**
@@ -258,7 +256,7 @@ public function test_detect_term_delete() {
 	 */
 	public function test_detect_term_delete_when_not_viewable() {
 		$instance = $this
-			->getMockBuilder( 'WPSEO_Slug_Change_Watcher' )
+			->getMockBuilder( WPSEO_Slug_Change_Watcher::class )
 			->setMethods( [ 'add_notification' ] )
 			->getMock();
 
@@ -268,7 +266,7 @@ public function test_detect_term_delete_when_not_viewable() {
 
 		$instance->register_hooks();
 
-		wp_delete_term( self::$nav_menu_id, 'nav_menu' );
+		\wp_delete_term( self::$nav_menu_id, 'nav_menu' );
 	}
 
 	/**
@@ -278,7 +276,7 @@ public function test_detect_term_delete_when_not_viewable() {
 	 */
 	public function test_detect_term_delete_when_not_exists() {
 		$instance = $this
-			->getMockBuilder( 'WPSEO_Slug_Change_Watcher' )
+			->getMockBuilder( WPSEO_Slug_Change_Watcher::class )
 			->setMethods( [ 'add_notification' ] )
 			->getMock();
 
@@ -288,6 +286,6 @@ public function test_detect_term_delete_when_not_exists() {
 
 		$instance->register_hooks();
 
-		wp_delete_term( 11111, 'category' );
+		\wp_delete_term( 11111, 'category' );
 	}
 }
diff --git a/tests/WP/Admin/test-class-yoast-form.php b/tests/WP/Admin/Yoast_Form_Test.php
similarity index 93%
rename from tests/WP/Admin/test-class-yoast-form.php
rename to tests/WP/Admin/Yoast_Form_Test.php
index fd7846930a6..fbb0cf4895c 100644
--- a/tests/WP/Admin/test-class-yoast-form.php
+++ b/tests/WP/Admin/Yoast_Form_Test.php
@@ -1,10 +1,8 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Admin
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Admin;
+
+use WPSEO_Options;
 use Yoast\WP\SEO\Tests\WP\Doubles\Admin\Yoast_Form_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
@@ -35,7 +33,7 @@ public function test_properties_set_with_valid_option() {
 	 */
 	public function test_properties_set_with_invalid_option() {
 		$option_keys = [ 'key1', 'key2', 'key3' ];
-		update_option( 'random', array_fill_keys( $option_keys, true ) );
+		\update_option( 'random', \array_fill_keys( $option_keys, true ) );
 
 		$form = new Yoast_Form_Double();
 		$form->set_option( 'random' );
diff --git a/tests/WP/Capabilities/test-class-capability-manager-factory.php b/tests/WP/Capability/Manager_Factory_Test.php
similarity index 76%
rename from tests/WP/Capabilities/test-class-capability-manager-factory.php
rename to tests/WP/Capability/Manager_Factory_Test.php
index 2a06ce12000..bbd8ac86f66 100644
--- a/tests/WP/Capabilities/test-class-capability-manager-factory.php
+++ b/tests/WP/Capability/Manager_Factory_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Capabilities
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Capability;
+
+use WPSEO_Capability_Manager_Factory;
 use Yoast\WPTestUtils\WPIntegration\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Capability_Manager_Factory_Test extends TestCase {
+class Manager_Factory_Test extends TestCase {
 
 	/**
 	 * Tests whether the same factory instance is returned when the get function is called twice.
diff --git a/tests/WP/Capabilities/test-class-capability-manager.php b/tests/WP/Capability/Manager_Test.php
similarity index 90%
rename from tests/WP/Capabilities/test-class-capability-manager.php
rename to tests/WP/Capability/Manager_Test.php
index a7300579ccc..591f7b6b499 100644
--- a/tests/WP/Capabilities/test-class-capability-manager.php
+++ b/tests/WP/Capability/Manager_Test.php
@@ -1,9 +1,6 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Capabilities
- */
+
+namespace Yoast\WP\SEO\Tests\WP\Capability;
 
 use Yoast\WP\SEO\Tests\WP\Doubles\Admin\Capability_Manager_Double;
 use Yoast\WPTestUtils\WPIntegration\TestCase;
@@ -11,7 +8,7 @@
 /**
  * Unit Test Class.
  */
-class Capability_Manager_Test extends TestCase {
+class Manager_Test extends TestCase {
 
 	/**
 	 * Tests whether capabilities are correctly registered.
@@ -78,11 +75,11 @@ public function test_register_add() {
 	public function test_filter_roles() {
 		$instance = new Capability_Manager_Double();
 
-		add_filter( 'capability_roles', [ $this, 'do_filter_roles' ] );
+		\add_filter( 'capability_roles', [ $this, 'do_filter_roles' ] );
 
 		$filtered = $instance->filter_roles( 'capability', [ 'role' ] );
 
-		remove_filter( 'capability_roles', [ $this, 'do_filter_roles' ] );
+		\remove_filter( 'capability_roles', [ $this, 'do_filter_roles' ] );
 
 		$this->assertEquals( $this->do_filter_roles( [ 'role' ] ), $filtered );
 	}
diff --git a/tests/WP/Capabilities/test-class-register-capabilities.php b/tests/WP/Capability/Register_Capabilities_Test.php
similarity index 88%
rename from tests/WP/Capabilities/test-class-register-capabilities.php
rename to tests/WP/Capability/Register_Capabilities_Test.php
index a224790ce98..380e25eff1b 100644
--- a/tests/WP/Capabilities/test-class-register-capabilities.php
+++ b/tests/WP/Capability/Register_Capabilities_Test.php
@@ -1,16 +1,16 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Capabilities
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Capability;
+
+use WPSEO_Capability_Manager_Factory;
+use WPSEO_Options;
+use WPSEO_Register_Capabilities;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Register_Capabilities_Test extends TestCase {
+class Register_Capabilities_Test extends TestCase {
 
 	/**
 	 * Tests whether the list of registered capabilities contains the correct capabilities.
@@ -48,9 +48,9 @@ public function test_filter_user_has_wpseo_manage_options_cap( $role, $access, $
 
 		WPSEO_Options::get_instance();
 
-		$options           = get_site_option( 'wpseo_ms', [] );
+		$options           = \get_site_option( 'wpseo_ms', [] );
 		$options['access'] = $access;
-		update_site_option( 'wpseo_ms', $options );
+		\update_site_option( 'wpseo_ms', $options );
 
 		WPSEO_Options::clear_cache();
 
@@ -59,7 +59,7 @@ public function test_filter_user_has_wpseo_manage_options_cap( $role, $access, $
 
 		if ( $role === 'network_administrator' ) {
 			$user = self::factory()->user->create_and_get( [ 'role' => 'administrator' ] );
-			grant_super_admin( $user->ID );
+			\grant_super_admin( $user->ID );
 		}
 		else {
 			$user = self::factory()->user->create_and_get( [ 'role' => $role ] );
diff --git a/tests/WP/Content_Type_Visibility/test-class-content-type-dismiss-new-route.php b/tests/WP/Content_Type_Visibility/Dismiss_New_Route_Test.php
similarity index 97%
rename from tests/WP/Content_Type_Visibility/test-class-content-type-dismiss-new-route.php
rename to tests/WP/Content_Type_Visibility/Dismiss_New_Route_Test.php
index e9953753471..8ad891349cc 100644
--- a/tests/WP/Content_Type_Visibility/test-class-content-type-dismiss-new-route.php
+++ b/tests/WP/Content_Type_Visibility/Dismiss_New_Route_Test.php
@@ -1,10 +1,11 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Content_Type_Visibility
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Content_Type_Visibility;
+
+use Mockery;
+use WP_REST_Request;
+use WP_REST_Response;
+use Yoast_Notification_Center;
 use Yoast\WP\SEO\Helpers\Options_Helper;
 use Yoast\WP\SEO\Content_Type_Visibility\Application\Content_Type_Visibility_Watcher_Actions;
 use Yoast\WP\SEO\Content_Type_Visibility\Application\Content_Type_Visibility_Dismiss_Notifications;
@@ -12,12 +13,11 @@
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
- * Class WPSEO_Content_Type_Visibility_Dismiss_Notifications_Test.
  * Integration Test Class for Content_Type_Visibility_Dismiss_Notifications and Content_Type_Visibility_Dismiss_New_Route classes.
  *
  * @coversDefaultClass Yoast\WP\SEO\Content_Type_Visibility\User_Interface\Content_Type_Visibility_Dismiss_New_Route
  */
-class Content_Type_Visibility_Dismiss_New_Route_Test extends TestCase {
+class Dismiss_New_Route_Test extends TestCase {
 
 	/**
 	 * The instance to test.
diff --git a/tests/WP/Formatter/test-metabox-formatter.php b/tests/WP/Formatter/Metabox_Formatter_Test.php
similarity index 79%
rename from tests/WP/Formatter/test-metabox-formatter.php
rename to tests/WP/Formatter/Metabox_Formatter_Test.php
index 96099445283..6419cfc5624 100644
--- a/tests/WP/Formatter/test-metabox-formatter.php
+++ b/tests/WP/Formatter/Metabox_Formatter_Test.php
@@ -1,16 +1,16 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Formatter
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Formatter;
+
+use WPSEO_Metabox_Formatter;
+use WPSEO_Post_Metabox_Formatter;
+use WPSEO_Utils;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Metabox_Formatter_Test extends TestCase {
+class Metabox_Formatter_Test extends TestCase {
 
 	/**
 	 * Test with getting the values.
@@ -32,9 +32,9 @@ public function test_getting_the_values() {
 		$result = $class_instance->get_values();
 
 		$this->assertEquals( 'Readability', $result['contentTab'] );
-		$this->assertTrue( array_key_exists( 'contentLocale', $result ) );
-		$this->assertTrue( array_key_exists( 'translations', $result ) );
-		$this->assertTrue( is_array( $result['translations'] ) );
+		$this->assertTrue( \array_key_exists( 'contentLocale', $result ) );
+		$this->assertTrue( \array_key_exists( 'translations', $result ) );
+		$this->assertTrue( \is_array( $result['translations'] ) );
 	}
 
 	/**
@@ -46,11 +46,11 @@ public function test_getting_the_values() {
 	 * @covers WPSEO_Metabox_Formatter::get_translations
 	 */
 	public function test_with_fake_language_file() {
-		$file_name = WPSEO_PATH . 'languages/wordpress-seo-' . get_user_locale() . '.json';
+		$file_name = \WPSEO_PATH . 'languages/wordpress-seo-' . \get_user_locale() . '.json';
 
 		// Make sure the folder exists.
-		wp_mkdir_p( WPSEO_PATH . 'languages' );
-		file_put_contents(
+		\wp_mkdir_p( \WPSEO_PATH . 'languages' );
+		\file_put_contents(
 			$file_name,
 			WPSEO_Utils::format_json_encode( [ 'key' => 'value' ] )
 		);
@@ -65,11 +65,11 @@ public function test_with_fake_language_file() {
 
 		$result = $class_instance->get_values();
 
-		$this->assertTrue( array_key_exists( 'translations', $result ) );
-		$this->assertTrue( is_array( $result['translations'] ) );
+		$this->assertTrue( \array_key_exists( 'translations', $result ) );
+		$this->assertTrue( \is_array( $result['translations'] ) );
 		$this->assertEquals( [ 'key' => 'value' ], $result['translations'] );
 
-		unlink( $file_name );
+		\unlink( $file_name );
 
 		$result = $class_instance->get_values();
 
@@ -83,7 +83,7 @@ public function test_with_fake_language_file() {
 	 * @covers Yoast\WP\SEO\Helpers\Language_Helper::is_word_form_recognition_active
 	 */
 	public function test_word_form_recognition_is_active() {
-		add_filter(
+		\add_filter(
 			'locale',
 			static function() {
 				return 'en_US';
@@ -111,7 +111,7 @@ static function() {
 	 * @covers Yoast\WP\SEO\Helpers\Language_Helper::is_word_form_recognition_active
 	 */
 	public function test_word_form_recognition_is_not_active() {
-		add_filter(
+		\add_filter(
 			'locale',
 			static function() {
 				return 'af_ZA';
diff --git a/tests/WP/Formatter/test-post-metabox-formatter.php b/tests/WP/Formatter/Post_Metabox_Formatter_Test.php
similarity index 85%
rename from tests/WP/Formatter/test-post-metabox-formatter.php
rename to tests/WP/Formatter/Post_Metabox_Formatter_Test.php
index 690d139c24d..b7028ceab7c 100644
--- a/tests/WP/Formatter/test-post-metabox-formatter.php
+++ b/tests/WP/Formatter/Post_Metabox_Formatter_Test.php
@@ -1,16 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Formatter
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Formatter;
+
+use WPSEO_Options;
+use WPSEO_Post_Metabox_Formatter;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Post_Metabox_Formatter_Test extends TestCase {
+class Post_Metabox_Formatter_Test extends TestCase {
 
 	/**
 	 * The post.
@@ -41,9 +40,9 @@ public function test_no_post_with_empty_options() {
 		$instance = new WPSEO_Post_Metabox_Formatter( null, [], '' );
 		$result   = $instance->get_values();
 
-		$this->assertEquals( $result['search_url'], admin_url( 'edit.php?seo_kw_filter={keyword}' ) );
-		$this->assertEquals( $result['post_edit_url'], admin_url( 'post.php?post={id}&action=edit' ) );
-		$this->assertEquals( $result['base_url'], YoastSEO()->helpers->url->home() );
+		$this->assertEquals( $result['search_url'], \admin_url( 'edit.php?seo_kw_filter={keyword}' ) );
+		$this->assertEquals( $result['post_edit_url'], \admin_url( 'post.php?post={id}&action=edit' ) );
+		$this->assertEquals( $result['base_url'], \YoastSEO()->helpers->url->home() );
 	}
 
 	/**
@@ -79,7 +78,7 @@ public function test_metabox_metadescription_date() {
 		$instance = new WPSEO_Post_Metabox_Formatter( $this->post, [], '' );
 		$result   = $instance->get_values();
 
-		$this->assertEquals( $result['metaDescriptionDate'], date_i18n( 'M j, Y', mysql2date( 'U', $this->post->post_date ) ) );
+		$this->assertEquals( $result['metaDescriptionDate'], \date_i18n( 'M j, Y', \mysql2date( 'U', $this->post->post_date ) ) );
 		$this->assertEquals( $result['title_template'], 'This is the title' );
 		$this->assertEquals( $result['metadesc_template'], 'This is the metadescription' );
 	}
@@ -97,7 +96,7 @@ public function test_post_on_add_page() {
 		$instance = new WPSEO_Post_Metabox_Formatter( $this->post, [], '' );
 		$result   = $instance->get_values();
 
-		$this->assertEquals( $result['base_url'], YoastSEO()->helpers->url->home() );
+		$this->assertEquals( $result['base_url'], \YoastSEO()->helpers->url->home() );
 
 		unset( $GLOBALS['pagenow'] );
 	}
@@ -138,6 +137,6 @@ public function test_with_unreplaceble_permalink_structure() {
 		$instance = new WPSEO_Post_Metabox_Formatter( $this->post, [], '%isnotreplaced%/' );
 		$result   = $instance->get_values();
 
-		$this->assertEquals( $result['base_url'], YoastSEO()->helpers->url->home() );
+		$this->assertEquals( $result['base_url'], \YoastSEO()->helpers->url->home() );
 	}
 }
diff --git a/tests/WP/Formatter/test-term-metabox-formatter.php b/tests/WP/Formatter/Term_Metabox_Formatter_Test.php
similarity index 81%
rename from tests/WP/Formatter/test-term-metabox-formatter.php
rename to tests/WP/Formatter/Term_Metabox_Formatter_Test.php
index 6f36206d2f2..d320ebdf541 100644
--- a/tests/WP/Formatter/test-term-metabox-formatter.php
+++ b/tests/WP/Formatter/Term_Metabox_Formatter_Test.php
@@ -1,16 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Formatter
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Formatter;
+
+use WPSEO_Options;
+use WPSEO_Term_Metabox_Formatter;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Term_Metabox_Formatter_Test extends TestCase {
+class Term_Metabox_Formatter_Test extends TestCase {
 
 	/**
 	 * Holds the term instance.
@@ -33,7 +32,7 @@ public function set_up() {
 		parent::set_up();
 
 		$this->term     = $this->factory->term->create_and_get();
-		$this->taxonomy = get_taxonomy( $this->term->taxonomy );
+		$this->taxonomy = \get_taxonomy( $this->term->taxonomy );
 	}
 
 	/**
@@ -46,9 +45,9 @@ public function test_no_taxonomy_no_term_and_no_options() {
 		$instance = new WPSEO_Term_Metabox_Formatter( null, null, [] );
 		$result   = $instance->get_values();
 
-		$this->assertFalse( array_key_exists( 'search_url', $result ) );
-		$this->assertFalse( array_key_exists( 'post_edit_url', $result ) );
-		$this->assertFalse( array_key_exists( 'base_url', $result ) );
+		$this->assertFalse( \array_key_exists( 'search_url', $result ) );
+		$this->assertFalse( \array_key_exists( 'post_edit_url', $result ) );
+		$this->assertFalse( \array_key_exists( 'base_url', $result ) );
 	}
 
 	/**
@@ -71,10 +70,10 @@ public function test_with_taxonomy_and_term_and_without_options() {
 
 		$result = $instance->get_values();
 
-		$this->assertEquals( $result['search_url'], admin_url( 'edit-tags.php?taxonomy=' . $this->term->taxonomy . '&seo_kw_filter={keyword}' ) );
-		$this->assertEquals( $result['post_edit_url'], admin_url( 'term.php?action=edit&taxonomy=' . $this->term->taxonomy . '&tag_ID={id}' ) );
+		$this->assertEquals( $result['search_url'], \admin_url( 'edit-tags.php?taxonomy=' . $this->term->taxonomy . '&seo_kw_filter={keyword}' ) );
+		$this->assertEquals( $result['post_edit_url'], \admin_url( 'term.php?action=edit&taxonomy=' . $this->term->taxonomy . '&tag_ID={id}' ) );
 
-		$this->assertEquals( trailingslashit( home_url( 'tag' ) ), $result['base_url'] );
+		$this->assertEquals( \trailingslashit( \home_url( 'tag' ) ), $result['base_url'] );
 		$this->assertEquals( [ '' => [] ], $result['keyword_usage'] );
 		$this->assertEquals( '%%term_title%% Archives %%page%% %%sep%% %%sitename%%', $result['title_template'] );
 		$this->assertEquals( '', $result['metadesc_template'] );
diff --git a/tests/WP/test-class-wpseo-breadcrumbs.php b/tests/WP/Frontend/Breadcrumbs_Test.php
similarity index 88%
rename from tests/WP/test-class-wpseo-breadcrumbs.php
rename to tests/WP/Frontend/Breadcrumbs_Test.php
index 802345a6510..20958485b96 100644
--- a/tests/WP/test-class-wpseo-breadcrumbs.php
+++ b/tests/WP/Frontend/Breadcrumbs_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Frontend;
+
+use WPSEO_Breadcrumbs;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Breadcrumbs_Test extends TestCase {
+class Breadcrumbs_Test extends TestCase {
 
 	/**
 	 * Placeholder test to prevent PHPUnit from throwing errors.
diff --git a/tests/WP/Frontend/test-class-wpseo-content-images.php b/tests/WP/Frontend/Content_Images_Test.php
similarity index 82%
rename from tests/WP/Frontend/test-class-wpseo-content-images.php
rename to tests/WP/Frontend/Content_Images_Test.php
index a082275abde..1d3df199785 100644
--- a/tests/WP/Frontend/test-class-wpseo-content-images.php
+++ b/tests/WP/Frontend/Content_Images_Test.php
@@ -1,9 +1,6 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests
- */
+
+namespace Yoast\WP\SEO\Tests\WP\Frontend;
 
 use Yoast\WP\SEO\Tests\WP\Doubles\Inc\Content_Images_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
@@ -13,7 +10,7 @@
  *
  * @group OpenGraph
  */
-class WPSEO_Content_Images_Test extends TestCase {
+class Content_Images_Test extends TestCase {
 
 	/**
 	 * Test getting the image from post content.
@@ -24,7 +21,7 @@ public function test_get_only_valid_images_from_content() {
 		$class_instance = new Content_Images_Double();
 
 		$external_image       = 'https://cdn.yoast.com/app/uploads/2018/03/Caroline_Blog_SEO_FI-600x314.jpg';
-		$non_attachment_image = get_home_url() . '/wp-content/plugins/wordpress-seo/tests/integration/assets/yoast.png';
+		$non_attachment_image = \get_home_url() . '/wp-content/plugins/wordpress-seo/tests/integration/assets/yoast.png';
 
 		// Create the post content.
 		$post_content = '<p>This is a post. It has several images:</p>
diff --git a/tests/WP/Frontend/test-front-end-integration.php b/tests/WP/Frontend/Front_End_Integration_Test.php
similarity index 96%
rename from tests/WP/Frontend/test-front-end-integration.php
rename to tests/WP/Frontend/Front_End_Integration_Test.php
index 4210ebbed98..30a70e73f7c 100644
--- a/tests/WP/Frontend/test-front-end-integration.php
+++ b/tests/WP/Frontend/Front_End_Integration_Test.php
@@ -1,10 +1,9 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Frontend
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Frontend;
+
+use Mockery;
+use WPSEO_Replace_Vars;
 use Yoast\WP\SEO\Helpers\Options_Helper;
 use Yoast\WP\SEO\Helpers\Request_Helper;
 use Yoast\WP\SEO\Integrations\Front_End_Integration;
@@ -16,7 +15,6 @@
 use YoastSEO_Vendor\Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
- * Class Front_End_Integration_Test.
  * Integration Test Class for the Front_End_Integration class.
  *
  * @coversDefaultClass Yoast\WP\SEO\Integrations\Front_End_Integration
@@ -68,7 +66,7 @@ class Front_End_Integration_Test extends TestCase {
 	/**
 	 * The instance.
 	 *
-	 * @var \Front_End_Integration_Double
+	 * @var Front_End_Integration_Double
 	 */
 	private $instance;
 
diff --git a/tests/WP/Frontend/test-class-wpseo-image-utils.php b/tests/WP/Frontend/Image_Utils_Test.php
similarity index 97%
rename from tests/WP/Frontend/test-class-wpseo-image-utils.php
rename to tests/WP/Frontend/Image_Utils_Test.php
index 8d7eeb58ce4..b440087e211 100644
--- a/tests/WP/Frontend/test-class-wpseo-image-utils.php
+++ b/tests/WP/Frontend/Image_Utils_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Frontend
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Frontend;
+
+use WPSEO_Image_Utils;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Tests WPSEO_Image_Utils.
  */
-final class WPSEO_Image_Utils_Test extends TestCase {
+final class Image_Utils_Test extends TestCase {
 
 	/**
 	 * Tests getting the full image for an existing attachment.
@@ -19,7 +17,7 @@ final class WPSEO_Image_Utils_Test extends TestCase {
 	 */
 	public function test_get_full_image() {
 		$attachment = self::factory()->attachment->create();
-		update_post_meta(
+		\update_post_meta(
 			$attachment,
 			'_wp_attachment_metadata',
 			[
@@ -51,7 +49,7 @@ public function test_get_full_image() {
 	 */
 	public function test_get_medium_image() {
 		$attachment = self::factory()->attachment->create();
-		update_post_meta(
+		\update_post_meta(
 			$attachment,
 			'_wp_attachment_metadata',
 			[
@@ -187,7 +185,7 @@ public function test_absolute_path( $input, $expected, $message = '' ) {
 	 * @return array Data.
 	 */
 	public function data_get_absolute_path() {
-		$uploads = wp_get_upload_dir();
+		$uploads = \wp_get_upload_dir();
 
 		return [
 			[
diff --git a/tests/WP/test-wpseo-functions.php b/tests/WP/Functions_Test.php
similarity index 92%
rename from tests/WP/test-wpseo-functions.php
rename to tests/WP/Functions_Test.php
index c411c335287..182b6136232 100644
--- a/tests/WP/test-wpseo-functions.php
+++ b/tests/WP/Functions_Test.php
@@ -1,16 +1,11 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests
- */
 
-use Yoast\WP\SEO\Tests\WP\TestCase;
+namespace Yoast\WP\SEO\Tests\WP;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Functions_Test extends TestCase {
+class Functions_Test extends TestCase {
 
 	/**
 	 * Tests whether wpseo_replace_vars correctly replaces replacevars.
@@ -36,16 +31,16 @@ public function test_wpseo_replace_vars() {
 				'post_content' => 'Post_Content',
 				'post_excerpt' => 'Post_Excerpt',
 				'post_author'  => $user_id,
-				'post_date'    => date( 'Y-m-d H:i:s', strtotime( '2000-01-01 2:30:00' ) ),
+				'post_date'    => \date( 'Y-m-d H:i:s', \strtotime( '2000-01-01 2:30:00' ) ),
 			]
 		);
 
 		// Get post.
-		$post = get_post( $post_id );
+		$post = \get_post( $post_id );
 
 		$input    = '%%title%% %%excerpt%% %%date%% %%name%%';
-		$expected = 'Post_Title Post_Excerpt ' . mysql2date( get_option( 'date_format' ), $post->post_date, true ) . ' User_Nicename';
-		$output   = wpseo_replace_vars( $input, (array) $post );
+		$expected = 'Post_Title Post_Excerpt ' . \mysql2date( \get_option( 'date_format' ), $post->post_date, true ) . ' User_Nicename';
+		$output   = \wpseo_replace_vars( $input, (array) $post );
 		$this->assertSame( $expected, $output );
 
 		/*
@@ -71,11 +66,11 @@ public function test_wpseo_replace_vars() {
 	 * @return void
 	 */
 	public function test_wpseo_replace_vars_excerpt( $post_data, $locale, $expected, $required_php_version = '' ) {
-		if ( $required_php_version !== '' && version_compare( PHP_VERSION, $required_php_version, '<' ) ) {
+		if ( $required_php_version !== '' && \version_compare( \PHP_VERSION, $required_php_version, '<' ) ) {
 			$this->markTestSkipped( 'This test requires PHP ' . $required_php_version . ' or higher' );
 		}
 
-		add_filter(
+		\add_filter(
 			'locale',
 			static function () use ( $locale ) {
 				return $locale;
@@ -84,13 +79,13 @@ static function () use ( $locale ) {
 
 		$post = null;
 		// Create post.
-		if ( is_array( $post_data ) ) {
+		if ( \is_array( $post_data ) ) {
 			$post_id = $this->factory->post->create( $post_data );
-			$post    = get_post( $post_id );
+			$post    = \get_post( $post_id );
 		}
 
 		$input  = 'The replaced excerpt: %%excerpt%%';
-		$output = wpseo_replace_vars( $input, (array) $post );
+		$output = \wpseo_replace_vars( $input, (array) $post );
 		$this->assertSame( $expected, $output );
 	}
 
@@ -217,7 +212,7 @@ public function provide_excerpt_replace_var_data() {
 
 		yield 'Trims leading and trailing newlines when generating an excerpt' => [
 			'post_data' => [
-				'post_content' => PHP_EOL . 'excerpt is generated from post content' . PHP_EOL,
+				'post_content' => \PHP_EOL . 'excerpt is generated from post content' . \PHP_EOL,
 				'post_excerpt' => '',
 			],
 			'locale'    => 'ja',
@@ -226,7 +221,7 @@ public function provide_excerpt_replace_var_data() {
 
 		yield 'Trims a combination of leading and trailing whitespace characters when generating an excerpt' => [
 			'post_data' => [
-				'post_content' => "\n\r  \t  excerpt is generated from post content \n\r 	  \n \r \t  " . PHP_EOL,
+				'post_content' => "\n\r  \t  excerpt is generated from post content \n\r 	  \n \r \t  " . \PHP_EOL,
 				'post_excerpt' => '',
 			],
 			'locale'    => 'en',
@@ -236,7 +231,7 @@ public function provide_excerpt_replace_var_data() {
 		yield 'Doesn\'t trim unicode whitespaces characters when generating an excerpt' => [
 			'post_data'            => [
 				// phpcs:ignore PHPCompatibility.TextStrings.NewUnicodeEscapeSequence -- This test is only ran on PHP 7 and up.
-				'post_content' => "excerpt is generated from post content \u{2002} " . PHP_EOL,
+				'post_content' => "excerpt is generated from post content \u{2002} " . \PHP_EOL,
 				'post_excerpt' => '',
 			],
 			'locale'               => 'en',
@@ -264,7 +259,7 @@ public function provide_excerpt_replace_var_data() {
 	 * @return void
 	 */
 	public function test_wpseo_get_capabilities() {
-		$capabilities = wpseo_get_capabilities();
+		$capabilities = \wpseo_get_capabilities();
 
 		$this->assertIsArray( $capabilities );
 	}
diff --git a/tests/WP/Helpers/test-first-time-configuration-notice-helper.php b/tests/WP/Helpers/First_Time_Configuration_Notice_Helper_Test.php
similarity index 97%
rename from tests/WP/Helpers/test-first-time-configuration-notice-helper.php
rename to tests/WP/Helpers/First_Time_Configuration_Notice_Helper_Test.php
index 550dbaa18ea..2666f7b9f5f 100644
--- a/tests/WP/Helpers/test-first-time-configuration-notice-helper.php
+++ b/tests/WP/Helpers/First_Time_Configuration_Notice_Helper_Test.php
@@ -1,17 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Helpers
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Helpers;
+
+use Mockery;
 use Yoast\WP\SEO\Helpers\First_Time_Configuration_Notice_Helper;
 use Yoast\WP\SEO\Helpers\Indexing_Helper;
 use Yoast\WP\SEO\Helpers\Options_Helper;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
- * Class First_Time_Configuration_Notice_Helper_Test.
  * Integration Test Class for the First_Time_Configuration_Notice_Helper class.
  *
  * @coversDefaultClass Yoast\WP\SEO\Helpers\First_Time_Configuration_Notice_Helper
@@ -196,7 +193,7 @@ public function test_first_time_configuration_not_finished( $user_role, $steps_c
 			->andReturn( $is_initial_indexing );
 
 		$user = self::factory()->user->create_and_get( [ 'role' => $user_role ] );
-		wp_set_current_user( $user->ID );
+		\wp_set_current_user( $user->ID );
 
 		$this->options_helper->set( 'first_time_install', $first_time_install );
 
diff --git a/tests/WP/Inc/test-class-wpseo-admin-bar-menu.php b/tests/WP/Inc/Admin_Bar_Menu_Test.php
similarity index 80%
rename from tests/WP/Inc/test-class-wpseo-admin-bar-menu.php
rename to tests/WP/Inc/Admin_Bar_Menu_Test.php
index f5724c14f68..0dcc376bf7c 100644
--- a/tests/WP/Inc/test-class-wpseo-admin-bar-menu.php
+++ b/tests/WP/Inc/Admin_Bar_Menu_Test.php
@@ -1,17 +1,21 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Inc
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Inc;
+
+use stdClass;
+use WP_Admin_Bar;
+use WPSEO_Admin_Asset_Manager;
+use WPSEO_Admin_Asset_SEO_Location;
+use WPSEO_Admin_Bar_Menu;
+use WPSEO_Meta;
+use WPSEO_Options;
 use Yoast\WP\SEO\Tests\WP\Doubles\Inc\Admin_Bar_Menu_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Admin_Bar_Menu_Test extends TestCase {
+class Admin_Bar_Menu_Test extends TestCase {
 
 	/**
 	 * WP SEO manager user ID.
@@ -50,15 +54,15 @@ class WPSEO_Admin_Bar_Menu_Test extends TestCase {
 	 * @return void
 	 */
 	public static function wpSetUpBeforeClass( $factory ) {
-		if ( ! class_exists( 'WP_Admin_Bar' ) ) {
-			require_once ABSPATH . WPINC . '/class-wp-admin-bar.php';
+		if ( ! \class_exists( WP_Admin_Bar::class ) ) {
+			require_once \ABSPATH . \WPINC . '/class-wp-admin-bar.php';
 		}
 
 		self::$wpseo_manager = $factory->user->create( [ 'role' => 'editor' ] );
-		get_userdata( self::$wpseo_manager )->add_cap( 'wpseo_manage_options' );
+		\get_userdata( self::$wpseo_manager )->add_cap( 'wpseo_manage_options' );
 
 		self::$network_administrator = $factory->user->create( [ 'role' => 'administrator' ] );
-		grant_super_admin( self::$network_administrator );
+		\grant_super_admin( self::$network_administrator );
 	}
 
 	/**
@@ -67,7 +71,7 @@ public static function wpSetUpBeforeClass( $factory ) {
 	 * @return void
 	 */
 	public static function wpTearDownAfterClass() {
-		revoke_super_admin( self::$network_administrator );
+		\revoke_super_admin( self::$network_administrator );
 		self::delete_user( self::$network_administrator );
 		self::delete_user( self::$wpseo_manager );
 	}
@@ -79,7 +83,7 @@ public static function wpTearDownAfterClass() {
 	 */
 	public function test_add_menu_lacking_capabilities() {
 		$admin_bar_menu = $this
-			->getMockBuilder( 'WPSEO_Admin_Bar_Menu' )
+			->getMockBuilder( WPSEO_Admin_Bar_Menu::class )
 			->setConstructorArgs( [ $this->get_asset_manager() ] )
 			->setMethods( $this->mock_wpseo_admin_bar_menu_methods )
 			->getMock();
@@ -121,12 +125,12 @@ public function test_add_menu_lacking_capabilities() {
 	 * @covers WPSEO_Admin_Bar_Menu::add_menu
 	 */
 	public function test_add_menu() {
-		wp_set_current_user( self::$wpseo_manager );
+		\wp_set_current_user( self::$wpseo_manager );
 
 		$wp_admin_bar = new WP_Admin_Bar();
 
 		$admin_bar_menu = $this
-			->getMockBuilder( 'WPSEO_Admin_Bar_Menu' )
+			->getMockBuilder( WPSEO_Admin_Bar_Menu::class )
 			->setConstructorArgs( [ $this->get_asset_manager() ] )
 			->setMethods( $this->mock_wpseo_admin_bar_menu_methods )
 			->getMock();
@@ -174,7 +178,7 @@ public function test_add_menu() {
 	 * @covers WPSEO_Admin_Bar_Menu::enqueue_assets
 	 */
 	public function test_enqueue_assets_without_admin_bar() {
-		add_filter( 'show_admin_bar', '__return_false' );
+		\add_filter( 'show_admin_bar', '__return_false' );
 
 		$asset_manager = $this->get_asset_manager( [ 'register_assets', 'enqueue_style' ] );
 
@@ -196,8 +200,8 @@ public function test_enqueue_assets_without_admin_bar() {
 	 * @covers WPSEO_Admin_Bar_Menu::enqueue_assets
 	 */
 	public function test_enqueue_assets() {
-		add_filter( 'show_admin_bar', '__return_true' );
-		wp_set_current_user( self::$wpseo_manager );
+		\add_filter( 'show_admin_bar', '__return_true' );
+		\wp_set_current_user( self::$wpseo_manager );
 
 		$asset_manager = $this->get_asset_manager( [ 'register_assets', 'enqueue_style' ] );
 
@@ -220,7 +224,7 @@ public function test_enqueue_assets() {
 	 * @covers WPSEO_Admin_Bar_Menu::register_hooks
 	 */
 	public function test_register_hooks() {
-		$admin_bar_menu = $this->getMockBuilder( 'WPSEO_Admin_Bar_Menu' )
+		$admin_bar_menu = $this->getMockBuilder( WPSEO_Admin_Bar_Menu::class )
 			->setConstructorArgs( [ $this->get_asset_manager() ] )
 			->setMethods( [ 'meets_requirements' ] )
 			->getMock();
@@ -231,9 +235,9 @@ public function test_register_hooks() {
 			->will( $this->returnValue( true ) );
 
 		$admin_bar_menu->register_hooks();
-		$this->assertIsInt( has_action( 'admin_bar_menu', [ $admin_bar_menu, 'add_menu' ], 95 ) );
-		$this->assertIsInt( has_action( 'wp_enqueue_scripts', [ $admin_bar_menu, 'enqueue_assets' ] ) );
-		$this->assertIsInt( has_action( 'admin_enqueue_scripts', [ $admin_bar_menu, 'enqueue_assets' ] ) );
+		$this->assertIsInt( \has_action( 'admin_bar_menu', [ $admin_bar_menu, 'add_menu' ], 95 ) );
+		$this->assertIsInt( \has_action( 'wp_enqueue_scripts', [ $admin_bar_menu, 'enqueue_assets' ] ) );
+		$this->assertIsInt( \has_action( 'admin_enqueue_scripts', [ $admin_bar_menu, 'enqueue_assets' ] ) );
 	}
 
 	/**
@@ -246,15 +250,15 @@ public function test_meets_requirements() {
 
 		WPSEO_Options::get_instance();
 
-		add_filter( 'option_wpseo', [ $this, 'filter_enable_admin_bar_menu_false' ], 9999 );
-		add_filter( 'default_option_wpseo', [ $this, 'filter_enable_admin_bar_menu_false' ], 9999 );
+		\add_filter( 'option_wpseo', [ $this, 'filter_enable_admin_bar_menu_false' ], 9999 );
+		\add_filter( 'default_option_wpseo', [ $this, 'filter_enable_admin_bar_menu_false' ], 9999 );
 		WPSEO_Options::clear_cache();
 
 		$first_result = $admin_bar_menu->meets_requirements();
 		$this->assertFalse( $first_result );
 
-		add_filter( 'option_wpseo', [ $this, 'filter_enable_admin_bar_menu_true' ], 10000 );
-		add_filter( 'default_option_wpseo', [ $this, 'filter_enable_admin_bar_menu_true' ], 10000 );
+		\add_filter( 'option_wpseo', [ $this, 'filter_enable_admin_bar_menu_true' ], 10000 );
+		\add_filter( 'default_option_wpseo', [ $this, 'filter_enable_admin_bar_menu_true' ], 10000 );
 		WPSEO_Options::clear_cache();
 
 		$second_result = $admin_bar_menu->meets_requirements();
@@ -305,7 +309,7 @@ public function test_get_post_focus_keyword_with_valid_object_but_no_id_property
 	 * @covers WPSEO_Admin_Bar_Menu::get_post_focus_keyword
 	 */
 	public function test_get_post_focus_keyword_with_page_analysis_filter_disabled() {
-		add_filter( 'wpseo_use_page_analysis', '__return_false' );
+		\add_filter( 'wpseo_use_page_analysis', '__return_false' );
 
 		$post     = self::factory()->post->create_and_get();
 		$instance = new Admin_Bar_Menu_Double();
@@ -348,12 +352,12 @@ public function filter_enable_admin_bar_menu_false( $result ) {
 	 */
 	protected function get_asset_manager( array $mock_methods = [] ) {
 		if ( empty( $mock_methods ) ) {
-			return new WPSEO_Admin_Asset_Manager( new WPSEO_Admin_Asset_SEO_Location( WP_PLUGIN_DIR . '/wordpress-seo/wp-seo.php' ) );
+			return new WPSEO_Admin_Asset_Manager( new WPSEO_Admin_Asset_SEO_Location( \WP_PLUGIN_DIR . '/wordpress-seo/wp-seo.php' ) );
 		}
 
 		return $this
-			->getMockBuilder( 'WPSEO_Admin_Asset_Manager' )
-			->setConstructorArgs( [ new WPSEO_Admin_Asset_SEO_Location( WP_PLUGIN_DIR . '/wordpress-seo/wp-seo.php' ) ] )
+			->getMockBuilder( WPSEO_Admin_Asset_Manager::class )
+			->setConstructorArgs( [ new WPSEO_Admin_Asset_SEO_Location( \WP_PLUGIN_DIR . '/wordpress-seo/wp-seo.php' ) ] )
 			->setMethods( $mock_methods )
 			->getMock();
 	}
diff --git a/tests/WP/test-class-wpseo-meta.php b/tests/WP/Inc/Meta_Test.php
similarity index 86%
rename from tests/WP/test-class-wpseo-meta.php
rename to tests/WP/Inc/Meta_Test.php
index 6d3501ccf10..e4845ce4177 100644
--- a/tests/WP/test-class-wpseo-meta.php
+++ b/tests/WP/Inc/Meta_Test.php
@@ -1,10 +1,8 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Inc;
+
+use WPSEO_Meta;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
@@ -12,7 +10,7 @@
  *
  * @todo Test for defaults.
  */
-class WPSEO_Meta_Test extends TestCase {
+class Meta_Test extends TestCase {
 
 	/**
 	 * Tests if data can be stored.
@@ -22,10 +20,10 @@ class WPSEO_Meta_Test extends TestCase {
 	public function test_set_value() {
 		// Create and go to post.
 		$post_id = $this->factory->post->create();
-		$this->go_to( get_permalink( $post_id ) );
+		$this->go_to( \get_permalink( $post_id ) );
 
 		WPSEO_Meta::set_value( 'test_set_value_key', 'test_set_value_value', $post_id );
-		$this->assertEquals( 'test_set_value_value', get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'test_set_value_key', true ) );
+		$this->assertEquals( 'test_set_value_value', \get_post_meta( $post_id, WPSEO_Meta::$meta_prefix . 'test_set_value_key', true ) );
 	}
 
 	/**
@@ -37,12 +35,12 @@ public function test_get_value() {
 
 		// Create and go to post.
 		$post_id = $this->factory->post->create();
-		$this->go_to( get_permalink( $post_id ) );
+		$this->go_to( \get_permalink( $post_id ) );
 
 		$key = 'test_get_value_key';
 		$this->register_meta_key( $key );
 
-		update_post_meta( $post_id, WPSEO_Meta::$meta_prefix . $key, 'test_get_value_value' );
+		\update_post_meta( $post_id, WPSEO_Meta::$meta_prefix . $key, 'test_get_value_value' );
 
 		$this->assertEquals( 'test_get_value_value', WPSEO_Meta::get_value( $key ) );
 	}
@@ -64,12 +62,12 @@ public function test_get_value_non_registered_field() {
 
 		// Create and go to post.
 		$post_id = $this->factory->post->create();
-		$this->go_to( get_permalink( $post_id ) );
+		$this->go_to( \get_permalink( $post_id ) );
 
 		$key = 'non_registered_key';
 
 		// The field exists on the post - because it will be saved.
-		update_post_meta( $post_id, WPSEO_Meta::$meta_prefix . $key, 'some_value' );
+		\update_post_meta( $post_id, WPSEO_Meta::$meta_prefix . $key, 'some_value' );
 
 		// As the field is not registered, we should ignore the value in the database.
 		$this->assertEquals( 'some_value', WPSEO_Meta::get_value( $key ) );
@@ -88,12 +86,12 @@ public function test_get_value_unregistered_field_serialized() {
 
 		// Create and go to post.
 		$post_id = $this->factory->post->create();
-		$this->go_to( get_permalink( $post_id ) );
+		$this->go_to( \get_permalink( $post_id ) );
 
 		$key = 'non_registered_key_array';
 
 		// The field exists on the post - because it will be saved.
-		update_post_meta( $post_id, WPSEO_Meta::$meta_prefix . $key, [ 'some_value' ] );
+		\update_post_meta( $post_id, WPSEO_Meta::$meta_prefix . $key, [ 'some_value' ] );
 
 		// As the field is not registered, we should ignore the value in the database.
 		$this->assertEquals( '', WPSEO_Meta::get_value( $key ) );
@@ -108,7 +106,7 @@ public function test_get_value_non_existing_key() {
 
 		// Create and go to post.
 		$post_id = $this->factory->post->create();
-		$this->go_to( get_permalink( $post_id ) );
+		$this->go_to( \get_permalink( $post_id ) );
 
 		// The post meta is never saved, so it is totally unknown.
 		$key = 'non_existing_key_2';
@@ -122,7 +120,7 @@ public function test_get_value_non_existing_key() {
 	 */
 	public function test_set_value_slashed() {
 		$post_id = $this->factory->post->create();
-		$this->go_to( get_permalink( $post_id ) );
+		$this->go_to( \get_permalink( $post_id ) );
 
 		$key = 'test_set_value_key_slashed';
 		$this->register_meta_key( $key );
@@ -142,7 +140,7 @@ public function test_set_value_slashed() {
 	 */
 	public function test_get_and_set_value_slashed_array() {
 		$post_id = $this->factory->post->create();
-		$this->go_to( get_permalink( $post_id ) );
+		$this->go_to( \get_permalink( $post_id ) );
 
 		$key = 'test_set_value_key_slashed_array';
 		$this->register_meta_key( $key, true );
@@ -162,13 +160,13 @@ public function test_get_and_set_value_slashed_array() {
 	 */
 	public function test_get_and_set_value_serialized_and_slashed_array() {
 		$post_id = $this->factory->post->create();
-		$this->go_to( get_permalink( $post_id ) );
+		$this->go_to( \get_permalink( $post_id ) );
 
 		$key = 'test_set_value_key_slashed_array';
 		$this->register_meta_key( $key, true );
 
 		$array = [ 'ke\\y' => '""slashed data" \\"' ];
-		$value = serialize( $array );
+		$value = \serialize( $array );
 
 		WPSEO_Meta::set_value( $key, $value, $post_id );
 		$this->assertEquals( $value, WPSEO_Meta::get_value( $key, $post_id ) );
@@ -190,10 +188,10 @@ public function test_remove_meta_if_default() {
 
 		// Set post meta to default value.
 		$default_value = WPSEO_Meta::$defaults[ $key ];
-		update_post_meta( $post_id, $key, $default_value );
+		\update_post_meta( $post_id, $key, $default_value );
 
 		// Default post meta should not be saved.
-		$meta_value = get_post_meta( $post_id, $key, true );
+		$meta_value = \get_post_meta( $post_id, $key, true );
 		$this->assertEquals( '', $meta_value );
 	}
 
@@ -205,17 +203,17 @@ public function test_remove_meta_if_default() {
 	public function test_dont_save_meta_if_default() {
 		// Create and go to post.
 		$post_id = $this->factory->post->create();
-		$this->go_to( get_permalink( $post_id ) );
+		$this->go_to( \get_permalink( $post_id ) );
 
 		// Generate key.
 		$key = WPSEO_Meta::$meta_prefix . 'meta-robots-noindex';
 
 		// Add default value to post_meta.
 		$default_value = WPSEO_Meta::$defaults[ $key ];
-		add_post_meta( $post_id, $key, $default_value );
+		\add_post_meta( $post_id, $key, $default_value );
 
 		// Default post meta should not be saved.
-		$meta_value = get_post_meta( $post_id, $key );
+		$meta_value = \get_post_meta( $post_id, $key );
 		$this->assertEquals( [], $meta_value );
 	}
 
diff --git a/tests/WP/Inc/test-class-myyoast-api-request.php b/tests/WP/Inc/MyYoast_Api_Request_Test.php
similarity index 90%
rename from tests/WP/Inc/test-class-myyoast-api-request.php
rename to tests/WP/Inc/MyYoast_Api_Request_Test.php
index 71f684ef82c..37a61656f85 100644
--- a/tests/WP/Inc/test-class-myyoast-api-request.php
+++ b/tests/WP/Inc/MyYoast_Api_Request_Test.php
@@ -1,10 +1,11 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Inc
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Inc;
+
+use WP_Error;
+use WPSEO_MyYoast_Api_Request;
+use WPSEO_MyYoast_Bad_Request_Exception;
+use WPSEO_Utils;
 use Yoast\WP\SEO\Tests\WP\Doubles\Inc\MyYoast_Api_Request_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
@@ -13,7 +14,7 @@
  *
  * @group MyYoast
  */
-class WPSEO_MyYoast_Api_Request_Test extends TestCase {
+class MyYoast_Api_Request_Test extends TestCase {
 
 	/**
 	 * Tests firing the request (happy path).
@@ -23,7 +24,7 @@ class WPSEO_MyYoast_Api_Request_Test extends TestCase {
 	 */
 	public function test_fire() {
 		$instance = $this
-			->getMockBuilder( 'WPSEO_MyYoast_Api_Request' )
+			->getMockBuilder( WPSEO_MyYoast_Api_Request::class )
 			->setMethods( [ 'do_request', 'decode_response' ] )
 			->setConstructorArgs( [ 'endpoint' ] )
 			->getMock();
@@ -50,7 +51,7 @@ public function test_fire() {
 	 */
 	public function test_fire_with_bad_request_exception_being_thrown() {
 		$instance = $this
-			->getMockBuilder( 'WPSEO_MyYoast_Api_Request' )
+			->getMockBuilder( WPSEO_MyYoast_Api_Request::class )
 			->setMethods( [ 'do_request', 'decode_response' ] )
 			->setConstructorArgs( [ 'endpoint' ] )
 			->getMock();
@@ -77,7 +78,7 @@ public function test_fire_with_bad_request_exception_being_thrown() {
 	 */
 	public function test_decode_response() {
 		$instance = $this
-			->getMockBuilder( 'WPSEO_MyYoast_Api_Request' )
+			->getMockBuilder( WPSEO_MyYoast_Api_Request::class )
 			->setMethods( [ 'do_request' ] )
 			->setConstructorArgs( [ 'endpoint' ] )
 			->getMock();
@@ -104,7 +105,7 @@ public function test_decode_response() {
 	 */
 	public function test_decode_response_wrong_output() {
 		$instance = $this
-			->getMockBuilder( 'WPSEO_MyYoast_Api_Request' )
+			->getMockBuilder( WPSEO_MyYoast_Api_Request::class )
 			->setMethods( [ 'do_request' ] )
 			->setConstructorArgs( [ 'endpoint' ] )
 			->getMock();
@@ -214,12 +215,12 @@ public function test_exception_arguments() {
 		$this->expectException( WPSEO_MyYoast_Bad_Request_Exception::class );
 		$this->expectExceptionMessage( 'Error' );
 
-		add_filter( 'pre_http_request', [ $this, 'return_error_object' ] );
+		\add_filter( 'pre_http_request', [ $this, 'return_error_object' ] );
 
 		$instance = new MyYoast_Api_Request_Double( 'some_url', [] );
 		$instance->do_request( 'some_url', [] );
 
-		remove_filter( 'pre_http_request', [ $this, 'return_error_object' ] );
+		\remove_filter( 'pre_http_request', [ $this, 'return_error_object' ] );
 	}
 
 	/**
diff --git a/tests/WP/Inc/Options/test-class-wpseo-option.php b/tests/WP/Inc/Options/Option_Test.php
similarity index 70%
rename from tests/WP/Inc/Options/test-class-wpseo-option.php
rename to tests/WP/Inc/Options/Option_Test.php
index 5a889805149..4f21cd755c1 100644
--- a/tests/WP/Inc/Options/test-class-wpseo-option.php
+++ b/tests/WP/Inc/Options/Option_Test.php
@@ -1,16 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Inc\Options
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Inc\Options;
+
+use WPSEO_Option;
+use WPSEO_Options;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Option_Test extends TestCase {
+class Option_Test extends TestCase {
 
 	/**
 	 * Tests that disabled variables cannot be updated.
@@ -33,10 +32,10 @@ public function test_prevent_disabled_options_update() {
 		}
 
 		// Unhook filters so that we can get the actual unaltered option value.
-		remove_all_filters( 'option_wpseo' );
+		\remove_all_filters( 'option_wpseo' );
 		$options  = WPSEO_Options::get_option( 'wpseo' );
-		$expected = array_fill_keys( $option_vars, true );
-		$this->assertEqualSets( $expected, array_intersect_key( $options, $expected ) );
+		$expected = \array_fill_keys( $option_vars, true );
+		$this->assertEqualSets( $expected, \array_intersect_key( $options, $expected ) );
 
 		foreach ( $option_vars as $option_var ) {
 			// Ensure the variable is disabled via the network.
@@ -47,9 +46,9 @@ public function test_prevent_disabled_options_update() {
 		}
 
 		// Unhook filters so that we can get the actual unaltered option value.
-		remove_all_filters( 'option_wpseo' );
+		\remove_all_filters( 'option_wpseo' );
 		$options  = WPSEO_Options::get_option( 'wpseo' );
-		$expected = array_fill_keys( $option_vars, true );
-		$this->assertEqualSets( $expected, array_intersect_key( $options, $expected ) );
+		$expected = \array_fill_keys( $option_vars, true );
+		$this->assertEqualSets( $expected, \array_intersect_key( $options, $expected ) );
 	}
 }
diff --git a/tests/WP/Inc/Options/test-class-wpseo-option-titles.php b/tests/WP/Inc/Options/Option_Titles_Test.php
similarity index 55%
rename from tests/WP/Inc/Options/test-class-wpseo-option-titles.php
rename to tests/WP/Inc/Options/Option_Titles_Test.php
index e4f98aa92c8..19786632159 100644
--- a/tests/WP/Inc/Options/test-class-wpseo-option-titles.php
+++ b/tests/WP/Inc/Options/Option_Titles_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Inc\Options
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Inc\Options;
+
+use WPSEO_Option_Titles;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Option_Titles_Test extends TestCase {
+class Option_Titles_Test extends TestCase {
 
 	/**
 	 * Tests if the enrich_defaults() cache is properly invalidated
@@ -22,18 +20,18 @@ public function test_enrich_defaults_cache_invalidation() {
 		$wpseo_option_titles = WPSEO_Option_Titles::get_instance();
 
 		// Register all actions again as they will have been removed in previous teardowns.
-		add_action( 'registered_post_type', [ $wpseo_option_titles, 'invalidate_enrich_defaults_cache' ] );
-		add_action( 'unregistered_post_type', [ $wpseo_option_titles, 'invalidate_enrich_defaults_cache' ] );
-		add_action( 'registered_taxonomy', [ $wpseo_option_titles, 'invalidate_enrich_defaults_cache' ] );
-		add_action( 'unregistered_taxonomy', [ $wpseo_option_titles, 'invalidate_enrich_defaults_cache' ] );
+		\add_action( 'registered_post_type', [ $wpseo_option_titles, 'invalidate_enrich_defaults_cache' ] );
+		\add_action( 'unregistered_post_type', [ $wpseo_option_titles, 'invalidate_enrich_defaults_cache' ] );
+		\add_action( 'registered_taxonomy', [ $wpseo_option_titles, 'invalidate_enrich_defaults_cache' ] );
+		\add_action( 'unregistered_taxonomy', [ $wpseo_option_titles, 'invalidate_enrich_defaults_cache' ] );
 
-		register_post_type( 'custom-post-type', [ 'public' => true ] );
+		\register_post_type( 'custom-post-type', [ 'public' => true ] );
 		$this->assertArrayHasKey( 'title-custom-post-type', $wpseo_option_titles->get_defaults() );
 
-		register_taxonomy( 'custom-taxonomy', 'post' );
+		\register_taxonomy( 'custom-taxonomy', 'post' );
 		$this->assertArrayHasKey( 'title-tax-custom-taxonomy', $wpseo_option_titles->get_defaults() );
 
-		unregister_taxonomy( 'custom-taxonomy' );
-		unregister_post_type( 'custom-post-type' );
+		\unregister_taxonomy( 'custom-taxonomy' );
+		\unregister_post_type( 'custom-post-type' );
 	}
 }
diff --git a/tests/WP/Inc/Options/test-class-wpseo-option-wpseo.php b/tests/WP/Inc/Options/Option_WPSEO_Test.php
similarity index 70%
rename from tests/WP/Inc/Options/test-class-wpseo-option-wpseo.php
rename to tests/WP/Inc/Options/Option_WPSEO_Test.php
index 023498b714e..2196a689194 100644
--- a/tests/WP/Inc/Options/test-class-wpseo-option-wpseo.php
+++ b/tests/WP/Inc/Options/Option_WPSEO_Test.php
@@ -1,16 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Inc\Options
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Inc\Options;
+
+use WPSEO_Option;
+use WPSEO_Options;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Option_WPSEO_Test extends TestCase {
+class Option_WPSEO_Test extends TestCase {
 
 	/**
 	 * Features which can be disabled via the network settings.
@@ -41,10 +40,10 @@ public function test_verify_features_against_network() {
 		$this->skipWithoutMultisite();
 
 		$options                               = WPSEO_Options::get_option( 'wpseo' );
-		$expected                              = array_fill_keys( $this->feature_vars, true );
+		$expected                              = \array_fill_keys( $this->feature_vars, true );
 		$expected['zapier_integration_active'] = false;
 		$expected['ryte_indexability']         = false;
-		$this->assertEqualSets( $expected, array_intersect_key( $options, $expected ) );
+		$this->assertEqualSets( $expected, \array_intersect_key( $options, $expected ) );
 
 		// Ensure the variables are disabled via the network.
 		foreach ( $this->feature_vars as $feature_var ) {
@@ -53,12 +52,12 @@ public function test_verify_features_against_network() {
 
 		// Test method directly.
 		$options  = WPSEO_Options::get_option_instance( 'wpseo' )->verify_features_against_network( $options );
-		$expected = array_fill_keys( $this->feature_vars, false );
-		$this->assertEqualSets( $expected, array_intersect_key( $options, $expected ) );
+		$expected = \array_fill_keys( $this->feature_vars, false );
+		$this->assertEqualSets( $expected, \array_intersect_key( $options, $expected ) );
 
 		// Test method integration with filters.
 		$options  = WPSEO_Options::get_option( 'wpseo' );
-		$expected = array_fill_keys( $this->feature_vars, false );
-		$this->assertEqualSets( $expected, array_intersect_key( $options, $expected ) );
+		$expected = \array_fill_keys( $this->feature_vars, false );
+		$this->assertEqualSets( $expected, \array_intersect_key( $options, $expected ) );
 	}
 }
diff --git a/tests/WP/Inc/Options/test-class-wpseo-options.php b/tests/WP/Inc/Options/Options_Test.php
similarity index 92%
rename from tests/WP/Inc/Options/test-class-wpseo-options.php
rename to tests/WP/Inc/Options/Options_Test.php
index 19a1eb563b5..76b2fd0c312 100644
--- a/tests/WP/Inc/Options/test-class-wpseo-options.php
+++ b/tests/WP/Inc/Options/Options_Test.php
@@ -1,16 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Inc\Options
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Inc\Options;
+
+use WPSEO_Option;
+use WPSEO_Options;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Options_Test extends TestCase {
+class Options_Test extends TestCase {
 
 	/**
 	 * Set up the class which will be tested.
@@ -114,7 +113,7 @@ public function test_get_returns_valid_result() {
 		$option                            = WPSEO_Options::get_option( 'wpseo' );
 		$option['keyword_analysis_active'] = true;
 		$option['show_onboarding_notice']  = false;
-		update_option( 'wpseo', $option );
+		\update_option( 'wpseo', $option );
 
 		$result = WPSEO_Options::get( 'keyword_analysis_active' );
 		$this->assertTrue( $result );
@@ -152,7 +151,7 @@ public function test_set_works() {
 		$option_before                            = WPSEO_Options::get_option( 'wpseo' );
 		$option_before['keyword_analysis_active'] = true;
 		$option_before['show_onboarding_notice']  = false;
-		update_option( 'wpseo', $option_before );
+		\update_option( 'wpseo', $option_before );
 
 		// Turn them around and see if they still return the correct value.
 		WPSEO_Options::set( 'keyword_analysis_active', false );
@@ -174,16 +173,16 @@ public function test_make_sure_keys_are_unique_over_options() {
 		$keys = [];
 
 		// Make sure the backfilling is not being done when determining "real" unique option names.
-		remove_all_actions( 'option_wpseo' );
-		remove_all_actions( 'option_wpseo_titles' );
+		\remove_all_actions( 'option_wpseo' );
+		\remove_all_actions( 'option_wpseo_titles' );
 
-		foreach ( array_keys( WPSEO_Options::$options ) as $option_name ) {
-			$option_keys = array_keys( WPSEO_Options::get_option( $option_name ) );
-			$intersected = array_intersect( $option_keys, $keys );
+		foreach ( \array_keys( WPSEO_Options::$options ) as $option_name ) {
+			$option_keys = \array_keys( WPSEO_Options::get_option( $option_name ) );
+			$intersected = \array_intersect( $option_keys, $keys );
 
 			$this->assertEquals( [], $intersected, 'Option keys must be unique (' . $option_name . ').' );
 
-			$keys = array_merge( $keys, $option_keys );
+			$keys = \array_merge( $keys, $option_keys );
 		}
 	}
 
diff --git a/tests/WP/Inc/Options/test-class-wpseo-taxonomy-meta.php b/tests/WP/Inc/Options/Taxonomy_Meta_Test.php
similarity index 97%
rename from tests/WP/Inc/Options/test-class-wpseo-taxonomy-meta.php
rename to tests/WP/Inc/Options/Taxonomy_Meta_Test.php
index 2def2743b60..84316458fc0 100644
--- a/tests/WP/Inc/Options/test-class-wpseo-taxonomy-meta.php
+++ b/tests/WP/Inc/Options/Taxonomy_Meta_Test.php
@@ -1,16 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Inc\Options
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Inc\Options;
+
+use WPSEO_Taxonomy_Meta;
+use WPSEO_Utils;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Taxonomy_Meta_Test extends TestCase {
+class Taxonomy_Meta_Test extends TestCase {
 
 	/**
 	 * Tests the method without a term object.
diff --git a/tests/WP/Inc/test-class-post-type.php b/tests/WP/Inc/Post_Type_Test.php
similarity index 83%
rename from tests/WP/Inc/test-class-post-type.php
rename to tests/WP/Inc/Post_Type_Test.php
index c70b8317ecb..30a592ff16f 100644
--- a/tests/WP/Inc/test-class-post-type.php
+++ b/tests/WP/Inc/Post_Type_Test.php
@@ -1,24 +1,23 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Inc
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Inc;
+
+use WPSEO_Options;
+use WPSEO_Post_Type;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Post_Type_Test extends TestCase {
+class Post_Type_Test extends TestCase {
 
 	/**
 	 * Remove the custom post type after each test.
 	 */
 	public function tear_down() {
 		// Remove possibly set post type.
-		unregister_post_type( 'custom-post-type' );
-		unregister_post_type( 'custom-post-type-api' );
+		\unregister_post_type( 'custom-post-type' );
+		\unregister_post_type( 'custom-post-type-api' );
 
 		parent::tear_down();
 	}
@@ -41,7 +40,7 @@ public function test_get_accessible_post_types() {
 	 * @covers WPSEO_Post_Type::get_accessible_post_types
 	 */
 	public function test_get_accessible_post_types_with_a_custom_post_type() {
-		register_post_type( 'custom-post-type', [ 'public' => true ] );
+		\register_post_type( 'custom-post-type', [ 'public' => true ] );
 
 		$this->assertContains( 'custom-post-type', WPSEO_Post_Type::get_accessible_post_types() );
 	}
@@ -52,7 +51,7 @@ public function test_get_accessible_post_types_with_a_custom_post_type() {
 	 * @covers WPSEO_Post_Type::get_accessible_post_types
 	 */
 	public function test_get_accessible_post_types_with_a_custom_post_type_that_is_noy_publicly_queryable() {
-		register_post_type(
+		\register_post_type(
 			'hidden-post-type',
 			[
 				'public'             => true,
@@ -69,7 +68,7 @@ public function test_get_accessible_post_types_with_a_custom_post_type_that_is_n
 	 * @covers WPSEO_Post_Type::get_accessible_post_types
 	 */
 	public function test_get_accessible_post_types_with_a_custom_private_post_type() {
-		register_post_type( 'custom-post-type', [ 'public' => false ] );
+		\register_post_type( 'custom-post-type', [ 'public' => false ] );
 
 		$this->assertNotContains( 'custom-post-type', WPSEO_Post_Type::get_accessible_post_types() );
 	}
@@ -80,7 +79,7 @@ public function test_get_accessible_post_types_with_a_custom_private_post_type()
 	 * @covers WPSEO_Post_Type::get_accessible_post_types
 	 */
 	public function test_get_accessible_post_types_with_a_non_indexable_post_type() {
-		$custom_post_type = register_post_type( 'custom-post-type', [ 'public' => true ] );
+		$custom_post_type = \register_post_type( 'custom-post-type', [ 'public' => true ] );
 
 		WPSEO_Options::set( 'noindex-' . $custom_post_type->name, true );
 
@@ -94,7 +93,7 @@ public function test_get_accessible_post_types_with_a_non_indexable_post_type()
 	 * @covers WPSEO_Post_Type::get_accessible_post_types
 	 */
 	public function test_get_accessible_post_types_with_an_indexable_post_type() {
-		$custom_post_type = register_post_type( 'custom-post-type', [ 'public' => true ] );
+		$custom_post_type = \register_post_type( 'custom-post-type', [ 'public' => true ] );
 
 		WPSEO_Options::set( 'noindex-' . $custom_post_type->name, false );
 
@@ -109,9 +108,9 @@ public function test_get_accessible_post_types_with_an_indexable_post_type() {
 	public function test_get_accessible_post_types_with_a_filter_hook() {
 		$this->assertContains( 'attachment', WPSEO_Post_Type::get_accessible_post_types() );
 
-		add_filter( 'wpseo_accessible_post_types', [ $this, 'filter_attachment' ] );
+		\add_filter( 'wpseo_accessible_post_types', [ $this, 'filter_attachment' ] );
 		$this->assertNotContains( 'attachment', WPSEO_Post_Type::get_accessible_post_types() );
-		remove_filter( 'wpseo_accessible_post_types', [ $this, 'filter_attachment' ] );
+		\remove_filter( 'wpseo_accessible_post_types', [ $this, 'filter_attachment' ] );
 	}
 
 	/**
@@ -120,11 +119,11 @@ public function test_get_accessible_post_types_with_a_filter_hook() {
 	 * @covers WPSEO_Post_Type::get_accessible_post_types
 	 */
 	public function test_get_accessible_post_types_with_a_filter_hook_that_returns_wrong_type() {
-		add_filter( 'wpseo_accessible_post_types', '__return_true' );
+		\add_filter( 'wpseo_accessible_post_types', '__return_true' );
 
 		$this->assertEquals( [], WPSEO_Post_Type::get_accessible_post_types() );
 
-		remove_filter( 'wpseo_accessible_post_types', '__return_true' );
+		\remove_filter( 'wpseo_accessible_post_types', '__return_true' );
 	}
 
 	/**
@@ -133,7 +132,7 @@ public function test_get_accessible_post_types_with_a_filter_hook_that_returns_w
 	 * @covers WPSEO_Post_Type::is_post_type_indexable
 	 */
 	public function test_is_post_type_indexable_with_indexable_post_type() {
-		$custom_post_type = register_post_type( 'custom-post-type', [ 'public' => true ] );
+		$custom_post_type = \register_post_type( 'custom-post-type', [ 'public' => true ] );
 
 		WPSEO_Options::set( 'noindex-' . $custom_post_type->name, false );
 
@@ -146,7 +145,7 @@ public function test_is_post_type_indexable_with_indexable_post_type() {
 	 * @covers WPSEO_Post_Type::is_post_type_indexable
 	 */
 	public function test_is_post_type_indexable_with_non_indexable_post_type() {
-		$custom_post_type = register_post_type( 'custom-post-type', [ 'public' => true ] );
+		$custom_post_type = \register_post_type( 'custom-post-type', [ 'public' => true ] );
 
 		WPSEO_Options::set( 'noindex-' . $custom_post_type->name, true );
 
@@ -192,7 +191,7 @@ public function test_rest_enabled_post_types() {
 		$this->assertTrue( WPSEO_Post_Type::is_rest_enabled( 'post' ) );
 		$this->assertFalse( WPSEO_Post_Type::is_rest_enabled( 'invalid_post_type' ) );
 
-		register_post_type(
+		\register_post_type(
 			'custom-post-type-api',
 			[
 				'public'       => true,
@@ -201,7 +200,7 @@ public function test_rest_enabled_post_types() {
 		);
 		$this->assertTrue( WPSEO_Post_Type::is_rest_enabled( 'custom-post-type-api' ) );
 
-		register_post_type( 'custom-post-type', [ 'public' => true ] );
+		\register_post_type( 'custom-post-type', [ 'public' => true ] );
 		$this->assertFalse( WPSEO_Post_Type::is_rest_enabled( 'custom-post-type' ) );
 	}
 }
diff --git a/tests/WP/Inc/test-class-wpseo-primary-term.php b/tests/WP/Inc/Primary_Term_Test.php
similarity index 84%
rename from tests/WP/Inc/test-class-wpseo-primary-term.php
rename to tests/WP/Inc/Primary_Term_Test.php
index b1f1b1057ab..858d9293859 100644
--- a/tests/WP/Inc/test-class-wpseo-primary-term.php
+++ b/tests/WP/Inc/Primary_Term_Test.php
@@ -1,17 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Inc
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Inc;
+
+use WPSEO_Primary_Term;
 use Yoast\WP\SEO\Tests\WP\Doubles\Inc\Primary_Term_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Primary_Term_Test extends TestCase {
+class Primary_Term_Test extends TestCase {
 
 	/**
 	 * Name of the taxonomy.
@@ -76,11 +74,11 @@ public function test_get_primary_term_WHERE_primary_term_DOES_NOT_EXIST_AND_term
 	 * @covers WPSEO_Primary_Term::get_primary_term
 	 */
 	public function test_get_primary_term_WHERE_primary_term_DOES_NOT_EXIST_AND_terms_EXIST() {
-		wp_insert_term( 'yoast', 'category' );
-		wp_insert_term( 'seo', 'category' );
+		\wp_insert_term( 'yoast', 'category' );
+		\wp_insert_term( 'seo', 'category' );
 
-		$term_first  = get_term_by( 'name', 'yoast', 'category' );
-		$term_second = get_term_by( 'name', 'seo', 'category' );
+		$term_first  = \get_term_by( 'name', 'yoast', 'category' );
+		$term_second = \get_term_by( 'name', 'seo', 'category' );
 
 		$post_id = $this->factory->post->create( [ 'post_category' => [ $term_first->term_id, $term_second->term_id ] ] );
 
@@ -99,6 +97,6 @@ public function test_set_primary_term_UPDATES_post_meta() {
 
 		$class_instance->set_primary_term( $this->primary_term_id );
 
-		$this->assertEquals( [ $this->primary_term_id ], get_post_meta( $this->post_id, '_yoast_wpseo_primary_' . $this->taxonomy_name ) );
+		$this->assertEquals( [ $this->primary_term_id ], \get_post_meta( $this->post_id, '_yoast_wpseo_primary_' . $this->taxonomy_name ) );
 	}
 }
diff --git a/tests/WP/test-class-wpseo-rank.php b/tests/WP/Inc/Rank_Test.php
similarity index 97%
rename from tests/WP/test-class-wpseo-rank.php
rename to tests/WP/Inc/Rank_Test.php
index 1649d8e073d..9ae0eaf123c 100644
--- a/tests/WP/test-class-wpseo-rank.php
+++ b/tests/WP/Inc/Rank_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Inc;
+
+use WPSEO_Rank;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Rank_Test extends TestCase {
+class Rank_Test extends TestCase {
 
 	/**
 	 * Tests whether the get_rank function returns the correct rank.
@@ -312,7 +310,7 @@ public function test_get_all_ranks() {
 		$ranks = WPSEO_Rank::get_all_ranks();
 
 		foreach ( $ranks as $rank ) {
-			$this->assertInstanceOf( 'WPSEO_Rank', $rank );
+			$this->assertInstanceOf( WPSEO_Rank::class, $rank );
 		}
 	}
 
@@ -325,7 +323,7 @@ public function test_get_all_readability_ranks() {
 		$ranks = WPSEO_Rank::get_all_readability_ranks();
 
 		foreach ( $ranks as $rank ) {
-			$this->assertInstanceOf( 'WPSEO_Rank', $rank );
+			$this->assertInstanceOf( WPSEO_Rank::class, $rank );
 		}
 	}
 
@@ -338,7 +336,7 @@ public function test_get_all_inclusive_language_ranks() {
 		$ranks = WPSEO_Rank::get_all_inclusive_language_ranks();
 
 		foreach ( $ranks as $rank ) {
-			$this->assertInstanceOf( 'WPSEO_Rank', $rank );
+			$this->assertInstanceOf( WPSEO_Rank::class, $rank );
 		}
 	}
 }
diff --git a/tests/WP/test-class-rewrite.php b/tests/WP/Inc/Rewrite_Test.php
similarity index 82%
rename from tests/WP/test-class-rewrite.php
rename to tests/WP/Inc/Rewrite_Test.php
index 43867db0d8f..aa0d887ac74 100644
--- a/tests/WP/test-class-rewrite.php
+++ b/tests/WP/Inc/Rewrite_Test.php
@@ -1,16 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Inc;
+
+use WPSEO_Options;
+use WPSEO_Rewrite;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Rewrite_Test extends TestCase {
+class Rewrite_Test extends TestCase {
 
 	/**
 	 * Name of the option indicating whether the rewrite options should be flushed.
@@ -41,7 +40,7 @@ public static function set_up_before_class() {
 	 */
 	public function test_schedule_flush() {
 		self::$class_instance->schedule_flush();
-		$this->assertIsInt( has_action( 'shutdown', 'flush_rewrite_rules' ) );
+		$this->assertIsInt( \has_action( 'shutdown', 'flush_rewrite_rules' ) );
 	}
 
 	/**
@@ -52,7 +51,7 @@ public function test_schedule_flush() {
 	public function test_no_category_base() {
 
 		$input         = 'http://yoast.com/cat/link/';
-		$category_base = get_option( 'category_base' );
+		$category_base = \get_option( 'category_base' );
 
 		if ( empty( $category_base ) ) {
 			$category_base = 'category';
@@ -62,13 +61,13 @@ public function test_no_category_base() {
 		 * Remove initial slash, if there is one (we remove the trailing slash in
 		 * the regex replacement and don't want to end up short a slash).
 		 */
-		if ( substr( $category_base, 0, 1 ) === '/' ) {
-			$category_base = substr( $category_base, 1 );
+		if ( \substr( $category_base, 0, 1 ) === '/' ) {
+			$category_base = \substr( $category_base, 1 );
 		}
 
 		$category_base .= '/';
 
-		$expected = preg_replace( '`' . preg_quote( $category_base, '`' ) . '`u', '', $input, 1 );
+		$expected = \preg_replace( '`' . \preg_quote( $category_base, '`' ) . '`u', '', $input, 1 );
 		$this->assertEquals( $expected, self::$class_instance->no_category_base( $input, null, 'category' ) ); // Passing null as 2nd parameter as it is not used.
 	}
 
@@ -92,7 +91,7 @@ public function test_query_vars() {
 	public function test_request_with_empty_query_vars() {
 
 		$instance = $this
-			->getMockBuilder( 'WPSEO_Rewrite' )
+			->getMockBuilder( WPSEO_Rewrite::class )
 			->setMethods( [ 'redirect' ] )
 			->getMock();
 		$instance
@@ -112,7 +111,7 @@ public function test_request_with_empty_query_vars() {
 	public function test_request_with_query_vars() {
 
 		$instance = $this
-			->getMockBuilder( 'WPSEO_Rewrite' )
+			->getMockBuilder( WPSEO_Rewrite::class )
 			->setMethods( [ 'redirect' ] )
 			->getMock();
 		$instance
@@ -132,9 +131,9 @@ public function test_category_rewrite_rules() {
 
 		$c = self::$class_instance;
 
-		$permalink_structure = get_option( 'permalink_structure' );
+		$permalink_structure = \get_option( 'permalink_structure' );
 
-		if ( ! ( is_multisite() && strpos( $permalink_structure, '/blog/' ) === 0 ) ) {
+		if ( ! ( \is_multisite() && \strpos( $permalink_structure, '/blog/' ) === 0 ) ) {
 			$expected = [
 				'(uncategorized)/(?:feed/)?(feed|rdf|rss|rss2|atom)/?$' => 'index.php?category_name=$matches[1]&feed=$matches[2]',
 				'(uncategorized)/page/?([0-9]{1,})/?$' => 'index.php?category_name=$matches[1]&paged=$matches[2]',
@@ -150,7 +149,7 @@ public function test_category_rewrite_rules() {
 		}
 
 		global $wp_rewrite;
-		$old_base = trim( str_replace( '%category%', '(.+)', $wp_rewrite->get_category_permastruct() ), '/' );
+		$old_base = \trim( \str_replace( '%category%', '(.+)', $wp_rewrite->get_category_permastruct() ), '/' );
 
 		$expected[ $old_base . '$' ] = 'index.php?wpseo_category_redirect=$matches[1]';
 
diff --git a/tests/WP/test-class-wpseo-statistics.php b/tests/WP/Inc/Statistics_Test.php
similarity index 70%
rename from tests/WP/test-class-wpseo-statistics.php
rename to tests/WP/Inc/Statistics_Test.php
index 08d9d4a6c04..45550142ee8 100644
--- a/tests/WP/test-class-wpseo-statistics.php
+++ b/tests/WP/Inc/Statistics_Test.php
@@ -1,16 +1,15 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Inc;
+
+use WPSEO_Rank;
+use WPSEO_Statistics;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Tests the WPSEO_Statistics class
  */
-class WPSEO_Statistics_Test extends TestCase {
+class Statistics_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
@@ -58,7 +57,7 @@ public function test_empty_statistics() {
 	public function test_filled_statistics_no_focus() {
 		$posts = $this->factory->post->create_many( 2, $this->default_post_args );
 
-		add_post_meta( $posts[1], '_yoast_wpseo_focuskw', 'focus keyword' );
+		\add_post_meta( $posts[1], '_yoast_wpseo_focuskw', 'focus keyword' );
 
 		$this->assertEquals( 1, $this->instance->get_post_count( new WPSEO_Rank( WPSEO_Rank::NO_FOCUS ) ) );
 	}
@@ -71,10 +70,10 @@ public function test_filled_statistics_no_focus() {
 	public function test_filled_statistics_bad() {
 		$posts = $this->factory->post->create_many( 4, $this->default_post_args );
 
-		add_post_meta( $posts[0], '_yoast_wpseo_linkdex', 0 ); // Not bad.
-		add_post_meta( $posts[1], '_yoast_wpseo_linkdex', 1 ); // Bad.
-		add_post_meta( $posts[2], '_yoast_wpseo_linkdex', 40 ); // Bad.
-		add_post_meta( $posts[3], '_yoast_wpseo_linkdex', 41 ); // Not bad.
+		\add_post_meta( $posts[0], '_yoast_wpseo_linkdex', 0 ); // Not bad.
+		\add_post_meta( $posts[1], '_yoast_wpseo_linkdex', 1 ); // Bad.
+		\add_post_meta( $posts[2], '_yoast_wpseo_linkdex', 40 ); // Bad.
+		\add_post_meta( $posts[3], '_yoast_wpseo_linkdex', 41 ); // Not bad.
 
 		$this->assertEquals( 2, $this->instance->get_post_count( new WPSEO_Rank( WPSEO_Rank::BAD ) ) );
 	}
@@ -87,10 +86,10 @@ public function test_filled_statistics_bad() {
 	public function test_filled_statistics_ok() {
 		$posts = $this->factory->post->create_many( 4, $this->default_post_args );
 
-		add_post_meta( $posts[0], '_yoast_wpseo_linkdex', 40 ); // Not OK.
-		add_post_meta( $posts[1], '_yoast_wpseo_linkdex', 41 ); // OK.
-		add_post_meta( $posts[2], '_yoast_wpseo_linkdex', 70 ); // OK.
-		add_post_meta( $posts[3], '_yoast_wpseo_linkdex', 71 ); // Not OK.
+		\add_post_meta( $posts[0], '_yoast_wpseo_linkdex', 40 ); // Not OK.
+		\add_post_meta( $posts[1], '_yoast_wpseo_linkdex', 41 ); // OK.
+		\add_post_meta( $posts[2], '_yoast_wpseo_linkdex', 70 ); // OK.
+		\add_post_meta( $posts[3], '_yoast_wpseo_linkdex', 71 ); // Not OK.
 
 		$this->assertEquals( 2, $this->instance->get_post_count( new WPSEO_Rank( WPSEO_Rank::OK ) ) );
 	}
@@ -103,10 +102,10 @@ public function test_filled_statistics_ok() {
 	public function test_filled_statistics_good() {
 		$posts = $this->factory->post->create_many( 4, $this->default_post_args );
 
-		add_post_meta( $posts[0], '_yoast_wpseo_linkdex', 70 ); // Not good.
-		add_post_meta( $posts[1], '_yoast_wpseo_linkdex', 71 ); // Good.
-		add_post_meta( $posts[2], '_yoast_wpseo_linkdex', 100 ); // Good.
-		add_post_meta( $posts[3], '_yoast_wpseo_linkdex', 101 ); // Not good.
+		\add_post_meta( $posts[0], '_yoast_wpseo_linkdex', 70 ); // Not good.
+		\add_post_meta( $posts[1], '_yoast_wpseo_linkdex', 71 ); // Good.
+		\add_post_meta( $posts[2], '_yoast_wpseo_linkdex', 100 ); // Good.
+		\add_post_meta( $posts[3], '_yoast_wpseo_linkdex', 101 ); // Not good.
 
 		$this->assertEquals( 2, $this->instance->get_post_count( new WPSEO_Rank( WPSEO_Rank::GOOD ) ) );
 	}
@@ -119,16 +118,16 @@ public function test_filled_statistics_good() {
 	public function test_all_statistics_published_posts() {
 		$posts = $this->factory->post->create_many( 4, $this->default_post_args );
 
-		add_post_meta( $posts[0], '_yoast_wpseo_linkdex', 0 ); // No-focus.
-		add_post_meta( $posts[0], '_yoast_wpseo_linkdex', 1 ); // Bad.
+		\add_post_meta( $posts[0], '_yoast_wpseo_linkdex', 0 ); // No-focus.
+		\add_post_meta( $posts[0], '_yoast_wpseo_linkdex', 1 ); // Bad.
 
-		add_post_meta( $posts[1], '_yoast_wpseo_linkdex', 41 ); // OK.
-		add_post_meta( $posts[1], '_yoast_wpseo_focuskw', 'focus keyword' );
+		\add_post_meta( $posts[1], '_yoast_wpseo_linkdex', 41 ); // OK.
+		\add_post_meta( $posts[1], '_yoast_wpseo_focuskw', 'focus keyword' );
 
-		add_post_meta( $posts[2], '_yoast_wpseo_linkdex', 71 ); // Good.
-		add_post_meta( $posts[2], '_yoast_wpseo_focuskw', 'focus keyword' );
+		\add_post_meta( $posts[2], '_yoast_wpseo_linkdex', 71 ); // Good.
+		\add_post_meta( $posts[2], '_yoast_wpseo_focuskw', 'focus keyword' );
 
-		add_post_meta( $posts[3], '_yoast_wpseo_focuskw', 'focus keyword' );
+		\add_post_meta( $posts[3], '_yoast_wpseo_focuskw', 'focus keyword' );
 
 		$this->assertEquals( 1, $this->instance->get_post_count( new WPSEO_Rank( WPSEO_Rank::BAD ) ) );
 		$this->assertEquals( 1, $this->instance->get_post_count( new WPSEO_Rank( WPSEO_Rank::OK ) ) );
@@ -144,10 +143,10 @@ public function test_all_statistics_published_posts() {
 	public function test_only_published_posts() {
 		$posts = $this->factory->post->create_many( 4, [ 'post_status' => 'draft' ] );
 
-		add_post_meta( $posts[0], '_yoast_wpseo_linkdex', 0 ); // No-focus.
-		add_post_meta( $posts[0], '_yoast_wpseo_linkdex', 1 ); // Bad.
-		add_post_meta( $posts[1], '_yoast_wpseo_linkdex', 41 ); // OK.
-		add_post_meta( $posts[2], '_yoast_wpseo_linkdex', 71 ); // Good.
+		\add_post_meta( $posts[0], '_yoast_wpseo_linkdex', 0 ); // No-focus.
+		\add_post_meta( $posts[0], '_yoast_wpseo_linkdex', 1 ); // Bad.
+		\add_post_meta( $posts[1], '_yoast_wpseo_linkdex', 41 ); // OK.
+		\add_post_meta( $posts[2], '_yoast_wpseo_linkdex', 71 ); // Good.
 
 		$this->assertEquals( 0, $this->instance->get_post_count( new WPSEO_Rank( WPSEO_Rank::BAD ) ) );
 		$this->assertEquals( 0, $this->instance->get_post_count( new WPSEO_Rank( WPSEO_Rank::OK ) ) );
@@ -164,7 +163,7 @@ public function test_no_index_statistics() {
 		$posts = $this->factory->post->create_many( 7, $this->default_post_args );
 
 		foreach ( $posts as $post_id ) {
-			add_post_meta( $post_id, '_yoast_wpseo_meta-robots-noindex', '1' );
+			\add_post_meta( $post_id, '_yoast_wpseo_meta-robots-noindex', '1' );
 		}
 
 		$this->assertEquals( 7, $this->instance->get_post_count( new WPSEO_Rank( WPSEO_Rank::NO_INDEX ) ) );
diff --git a/tests/WP/Inc/test-class-wpseo-upgrade-history.php b/tests/WP/Inc/Upgrade_History_Test.php
similarity index 90%
rename from tests/WP/Inc/test-class-wpseo-upgrade-history.php
rename to tests/WP/Inc/Upgrade_History_Test.php
index 601b93e1a5b..fce82b8c92b 100644
--- a/tests/WP/Inc/test-class-wpseo-upgrade-history.php
+++ b/tests/WP/Inc/Upgrade_History_Test.php
@@ -1,10 +1,8 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Inc;
+
+use WPSEO_Upgrade_History;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
@@ -12,7 +10,7 @@
  *
  * @group upgrades
  */
-class WPSEO_Upgrade_History_Test extends TestCase {
+class Upgrade_History_Test extends TestCase {
 
 	/**
 	 * Option name.
@@ -34,7 +32,7 @@ private function get_instance() {
 	 * Removes the used option.
 	 */
 	public function tear_down() {
-		delete_option( self::$option_name );
+		\delete_option( self::$option_name );
 
 		parent::tear_down();
 	}
@@ -84,15 +82,15 @@ public function test_get_empty() {
 	 */
 	public function test_add() {
 		// This must contain something.
-		update_option( 'mock_option_name', 'mock_data' );
+		\update_option( 'mock_option_name', 'mock_data' );
 
 		$upgrade_history = $this->get_instance();
 		$upgrade_history->add( '1.0.0', '2.0.0', [ 'mock_option_name' ] );
 
-		delete_option( 'mock_option_name' );
+		\delete_option( 'mock_option_name' );
 
 		$history = $upgrade_history->get();
-		$entry   = current( $history );
+		$entry   = \current( $history );
 
 		$this->assertArrayHasKey( 'old_version', $entry );
 		$this->assertArrayHasKey( 'new_version', $entry );
@@ -111,7 +109,7 @@ public function test_add_no_options() {
 		$upgrade_history->add( '1.0.0', '2.0.0', [] );
 
 		$history = $upgrade_history->get();
-		$entry   = current( $history );
+		$entry   = \current( $history );
 
 		$this->assertIsArray( $entry, 'There should be an entry added.' );
 		$this->assertArrayHasKey( 'options', $entry );
@@ -130,7 +128,7 @@ public function test_add_empty_option() {
 		$upgrade_history->add( '1.0.0', '2.0.0', [ 'option_does_not_exist' ] );
 
 		$history = $upgrade_history->get();
-		$entry   = current( $history );
+		$entry   = \current( $history );
 
 		$this->assertIsArray( $entry, 'There should be an entry added.' );
 		$this->assertArrayHasKey( 'options', $entry );
diff --git a/tests/WP/Inc/test-class-wpseo-upgrade.php b/tests/WP/Inc/Upgrade_Test.php
similarity index 79%
rename from tests/WP/Inc/test-class-wpseo-upgrade.php
rename to tests/WP/Inc/Upgrade_Test.php
index 1bc2333435a..8654ca539d3 100644
--- a/tests/WP/Inc/test-class-wpseo-upgrade.php
+++ b/tests/WP/Inc/Upgrade_Test.php
@@ -1,10 +1,9 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Inc;
+
+use stdClass;
+use WPSEO_Options;
 use Yoast\WP\SEO\Tests\WP\Doubles\Inc\Upgrade_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
@@ -13,7 +12,7 @@
  *
  * @group upgrades
  */
-class WPSEO_Upgrade_Test extends TestCase {
+class Upgrade_Test extends TestCase {
 
 	/**
 	 * Retrieves the instance to test against.
@@ -39,7 +38,7 @@ public function test_get_option_from_database() {
 
 		$instance = $this->get_instance();
 
-		update_option( 'some_option', $content );
+		\update_option( 'some_option', $content );
 
 		$this->assertEquals( $content, $instance->get_option_from_database( 'some_option' ) );
 	}
@@ -59,14 +58,14 @@ public function test_get_option_from_database_no_filters_applied() {
 
 		$instance = $this->get_instance();
 
-		update_option( 'some_option', $content );
+		\update_option( 'some_option', $content );
 
-		add_filter( 'pre_option_some_option', [ $this, 'return_override' ] );
+		\add_filter( 'pre_option_some_option', [ $this, 'return_override' ] );
 
-		$this->assertEquals( $this->return_override(), get_option( 'some_option' ) );
+		$this->assertEquals( $this->return_override(), \get_option( 'some_option' ) );
 		$this->assertEquals( $content, $instance->get_option_from_database( 'some_option' ) );
 
-		remove_filter( 'pre_option_some_option', [ $this, 'return_override' ] );
+		\remove_filter( 'pre_option_some_option', [ $this, 'return_override' ] );
 	}
 
 	/**
@@ -90,20 +89,20 @@ public function test_cleanup_option_data() {
 
 		$original = [
 			'invalid_key' => true,
-			'version'     => WPSEO_VERSION,
+			'version'     => \WPSEO_VERSION,
 		];
 
 		// Set option with invalid keys in the database.
 		$this->set_option_in_database( 'wpseo', $original );
 
 		// The key should be present on the option.
-		$this->assertArrayHasKey( 'invalid_key', get_option( 'wpseo' ) );
+		$this->assertArrayHasKey( 'invalid_key', \get_option( 'wpseo' ) );
 
 		// Cleaning up the option.
 		$instance->cleanup_option_data( 'wpseo' );
 
 		// Make sure the key has been removed.
-		$this->assertArrayNotHasKey( 'invalid_key', get_option( 'wpseo' ) );
+		$this->assertArrayNotHasKey( 'invalid_key', \get_option( 'wpseo' ) );
 	}
 
 	/**
@@ -116,7 +115,7 @@ public function test_cleanup_option_data_no_data() {
 
 		$instance->cleanup_option_data( 'random_option' );
 
-		$this->assertNull( get_option( 'random_option', null ) );
+		$this->assertNull( \get_option( 'random_option', null ) );
 	}
 
 	/**
@@ -169,19 +168,19 @@ public function test_save_option_setting_not_set() {
 	public function test_finish_up() {
 		$instance = $this->get_instance();
 
-		delete_option( 'wpseo' );
-		delete_option( 'wpseo_titles' );
-		delete_option( 'wpseo_social' );
+		\delete_option( 'wpseo' );
+		\delete_option( 'wpseo_titles' );
+		\delete_option( 'wpseo_social' );
 
 		$instance->finish_up();
 
-		$this->assertEquals( WPSEO_VERSION, WPSEO_Options::get( 'version' ) );
-		$this->assertTrue( has_action( 'shutdown', 'flush_rewrite_rules' ) > 0 );
+		$this->assertEquals( \WPSEO_VERSION, WPSEO_Options::get( 'version' ) );
+		$this->assertTrue( \has_action( 'shutdown', 'flush_rewrite_rules' ) > 0 );
 
 		// Ensure options exist.
-		$this->assertNotEmpty( get_option( 'wpseo' ) );
-		$this->assertNotEmpty( get_option( 'wpseo_titles' ) );
-		$this->assertNotEmpty( get_option( 'wpseo_social' ) );
+		$this->assertNotEmpty( \get_option( 'wpseo' ) );
+		$this->assertNotEmpty( \get_option( 'wpseo_titles' ) );
+		$this->assertNotEmpty( \get_option( 'wpseo_social' ) );
 	}
 
 	/**
@@ -209,7 +208,7 @@ private function set_option_in_database( $option_name, $option_value ) {
 			[
 				'option_name'  => $option_name,
 				// phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.serialize_serialize -- Reason: There's no security risk, because users don't interact with tests.
-				'option_value' => serialize( $option_value ),
+				'option_value' => \serialize( $option_value ),
 			],
 			[ 'option_name' => $option_name ]
 		);
diff --git a/tests/WP/test-class-wpseo-utils.php b/tests/WP/Inc/Utils_Test.php
similarity index 96%
rename from tests/WP/test-class-wpseo-utils.php
rename to tests/WP/Inc/Utils_Test.php
index 41c66cac75a..fc8f0d0072e 100644
--- a/tests/WP/test-class-wpseo-utils.php
+++ b/tests/WP/Inc/Utils_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Inc;
+
+use WPSEO_Utils;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Utils_Test extends TestCase {
+class Utils_Test extends TestCase {
 
 	/**
 	 * Tests whether is_apache correctly returns if the site runs on apache.
@@ -153,9 +151,9 @@ public function test_retrieve_enabled_features_with_filter() {
 		// Features we expect to be added by the filter.
 		$added_features = [ 'OTHER_FEATURE', 'ANOTHER_FEATURE' ];
 		// Expected features are the ones in the PHP constant + the features added by the filter.
-		$expected = array_merge( $expected, $added_features );
+		$expected = \array_merge( $expected, $added_features );
 
-		add_filter( 'wpseo_enable_feature', [ $this, 'filter_wpseo_enable_feature' ] );
+		\add_filter( 'wpseo_enable_feature', [ $this, 'filter_wpseo_enable_feature' ] );
 		$this->assertEquals( $expected, WPSEO_Utils::retrieve_enabled_features() );
 	}
 
@@ -169,7 +167,7 @@ public function test_retrieve_enabled_features_with_filter() {
 	public function filter_wpseo_enable_feature( $enabled_features ) {
 		$second_array = [ 'OTHER_FEATURE', 'ANOTHER_FEATURE' ];
 
-		return array_merge( $enabled_features, $second_array );
+		return \array_merge( $enabled_features, $second_array );
 	}
 
 	/**
diff --git a/tests/WP/Notifications/test-class-yoast-notification-center.php b/tests/WP/Notifications/Yoast_Notification_Center_Test.php
similarity index 89%
rename from tests/WP/Notifications/test-class-yoast-notification-center.php
rename to tests/WP/Notifications/Yoast_Notification_Center_Test.php
index 2f67a244a21..43190383426 100644
--- a/tests/WP/Notifications/test-class-yoast-notification-center.php
+++ b/tests/WP/Notifications/Yoast_Notification_Center_Test.php
@@ -1,12 +1,12 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package Yoast\Tests\Notifications
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Notifications;
+
+use WP_User;
 use Yoast\WP\SEO\Tests\WP\Doubles\Admin\Yoast_Notification_Center_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
+use Yoast_Notification;
+use Yoast_Notification_Center;
 
 /**
  * Class Test_Yoast_Notification_Center.
@@ -43,7 +43,7 @@ public function set_up() {
 		$user = new WP_User( $this->user_id );
 		$user->add_cap( 'wpseo_manage_options' );
 
-		wp_set_current_user( $this->user_id );
+		\wp_set_current_user( $this->user_id );
 	}
 
 	/**
@@ -126,7 +126,7 @@ public function test_is_notification_dismissed() {
 		$notification_dismissal_key = 'notification_dismissal';
 		$notification               = new Yoast_Notification( 'dismiss', [ 'dismissal_key' => $notification_dismissal_key ] );
 
-		update_user_meta( $this->user_id, $notification_dismissal_key, '1' );
+		\update_user_meta( $this->user_id, $notification_dismissal_key, '1' );
 
 		$subject = $this->get_notification_center();
 		$this->assertTrue( $subject->is_notification_dismissed( $notification ) );
@@ -142,7 +142,7 @@ public function test_clear_dismissal() {
 
 		$subject = $this->get_notification_center();
 
-		update_user_meta( $this->user_id, $notification->get_dismissal_key(), '1' );
+		\update_user_meta( $this->user_id, $notification->get_dismissal_key(), '1' );
 
 		$this->assertTrue( $subject->is_notification_dismissed( $notification ) );
 
@@ -161,7 +161,7 @@ public function test_clear_dismissal_as_string() {
 
 		$subject = $this->get_notification_center();
 
-		update_user_meta( $this->user_id, $notification->get_dismissal_key(), '1' );
+		\update_user_meta( $this->user_id, $notification->get_dismissal_key(), '1' );
 
 		$this->assertTrue( $subject->is_notification_dismissed( $notification ) );
 
@@ -200,7 +200,7 @@ public function test_update_storage() {
 
 		$subject->update_storage();
 
-		$stored_notifications = get_user_option( Yoast_Notification_Center::STORAGE_KEY, $this->user_id );
+		$stored_notifications = \get_user_option( Yoast_Notification_Center::STORAGE_KEY, $this->user_id );
 
 		$test = [ $notification->to_array() ];
 
@@ -221,7 +221,7 @@ public function test_update_storage_non_persistent() {
 
 		$subject->update_storage();
 
-		$stored_notifications = get_option( Yoast_Notification_Center::STORAGE_KEY );
+		$stored_notifications = \get_option( Yoast_Notification_Center::STORAGE_KEY );
 
 		$this->assertFalse( $stored_notifications );
 	}
@@ -356,7 +356,7 @@ public function test_display_notifications() {
 		$options = [];
 
 		$notification = $this
-			->getMockBuilder( 'Yoast_Notification' )
+			->getMockBuilder( Yoast_Notification::class )
 			->setConstructorArgs( [ $message, $options ] )
 			->setMethods( [ 'display_for_current_user', '__toString' ] )
 			->getMock();
@@ -388,7 +388,7 @@ public function test_display_notifications_not_for_current_user() {
 		$options = [];
 
 		$notification = $this
-			->getMockBuilder( 'Yoast_Notification' )
+			->getMockBuilder( Yoast_Notification::class )
 			->setConstructorArgs( [ $message, $options ] )
 			->setMethods( [ 'display_for_current_user', '__toString' ] )
 			->getMock();
@@ -428,7 +428,7 @@ public function test_display_dismissed_notification() {
 		$notification = new Yoast_Notification( $message, $options );
 
 		// Dismiss the key for the current user.
-		update_user_meta( $this->user_id, $notification_dismissal_key, '1' );
+		\update_user_meta( $this->user_id, $notification_dismissal_key, '1' );
 
 		// Add the notification.
 		$subject = $this->get_notification_center();
@@ -466,7 +466,7 @@ public function test_update_nonce_on_re_add_notification() {
 
 		$this->assertIsArray( $notifications );
 
-		$notification = array_shift( $notifications );
+		$notification = \array_shift( $notifications );
 
 		$this->assertNotEquals( $notification->get_nonce(), $old_nonce );
 	}
@@ -501,7 +501,7 @@ public function test_resolved_notifications() {
 		$count               = $notification_center->get_resolved_notification_count();
 
 		// Apply max for static test problems.
-		$this->assertEquals( 0, max( 0, $count ) );
+		$this->assertEquals( 0, \max( 0, $count ) );
 	}
 
 	/**
@@ -513,7 +513,7 @@ public function test_maybe_dismiss_notification() {
 		$a = new Yoast_Notification( 'a' );
 		$this->assertFalse( Yoast_Notification_Center::maybe_dismiss_notification( $a ) );
 
-		$b = new Yoast_Notification( 'b', [ 'id' => uniqid( 'id', true ) ] );
+		$b = new Yoast_Notification( 'b', [ 'id' => \uniqid( 'id', true ) ] );
 		$this->assertFalse( Yoast_Notification_Center::maybe_dismiss_notification( $b ) );
 	}
 
@@ -552,11 +552,11 @@ public function test_dismiss_notification_is_per_site() {
 		// Dismiss notification for the current site.
 		Yoast_Notification_Center::dismiss_notification( $notification );
 
-		$site1_dismissed = (bool) get_user_option( $dismissal_key, $this->user_id );
+		$site1_dismissed = (bool) \get_user_option( $dismissal_key, $this->user_id );
 
-		switch_to_blog( $site2 );
-		$site2_dismissed = (bool) get_user_option( $dismissal_key, $this->user_id );
-		restore_current_blog();
+		\switch_to_blog( $site2 );
+		$site2_dismissed = (bool) \get_user_option( $dismissal_key, $this->user_id );
+		\restore_current_blog();
 
 		$this->assertTrue( $site1_dismissed );
 		$this->assertFalse( $site2_dismissed );
@@ -578,19 +578,19 @@ public function test_restore_notification_is_per_site() {
 		$dismissal_key = $notification->get_dismissal_key();
 
 		// Dismiss notification for both sites.
-		update_user_option( $this->user_id, $dismissal_key, 'seen' );
-		switch_to_blog( $site2 );
-		update_user_option( $this->user_id, $dismissal_key, 'seen' );
-		restore_current_blog();
+		\update_user_option( $this->user_id, $dismissal_key, 'seen' );
+		\switch_to_blog( $site2 );
+		\update_user_option( $this->user_id, $dismissal_key, 'seen' );
+		\restore_current_blog();
 
 		// Restore notification for the current site.
 		Yoast_Notification_Center::restore_notification( $notification );
 
-		$site1_dismissed = (bool) get_user_option( $dismissal_key, $this->user_id );
+		$site1_dismissed = (bool) \get_user_option( $dismissal_key, $this->user_id );
 
-		switch_to_blog( $site2 );
-		$site2_dismissed = (bool) get_user_option( $dismissal_key, $this->user_id );
-		restore_current_blog();
+		\switch_to_blog( $site2 );
+		$site2_dismissed = (bool) \get_user_option( $dismissal_key, $this->user_id );
+		\restore_current_blog();
 
 		$this->assertFalse( $site1_dismissed );
 		$this->assertTrue( $site2_dismissed );
@@ -612,13 +612,13 @@ public function test_is_notification_dismissed_is_per_site() {
 		$dismissal_key = $notification->get_dismissal_key();
 
 		// Dismiss notification for the current site.
-		update_user_option( $this->user_id, $dismissal_key, 'seen' );
+		\update_user_option( $this->user_id, $dismissal_key, 'seen' );
 
 		$site1_dismissed = Yoast_Notification_Center::is_notification_dismissed( $notification );
 
-		switch_to_blog( $site2 );
+		\switch_to_blog( $site2 );
 		$site2_dismissed = Yoast_Notification_Center::is_notification_dismissed( $notification );
-		restore_current_blog();
+		\restore_current_blog();
 
 		$this->assertTrue( $site1_dismissed );
 		$this->assertFalse( $site2_dismissed );
@@ -635,15 +635,15 @@ public function test_is_notification_dismissed_falls_back_to_user_meta() {
 		$dismissal_key = $notification->get_dismissal_key();
 
 		// Dismiss notification in the old incorrect way.
-		update_user_meta( $this->user_id, $dismissal_key, 'seen' );
+		\update_user_meta( $this->user_id, $dismissal_key, 'seen' );
 
 		$dismissed = Yoast_Notification_Center::is_notification_dismissed( $notification );
 
 		$this->assertTrue( $dismissed );
 
 		// Ensure the old user metadata has been migrated on-the-fly.
-		$this->assertSame( 'seen', get_user_option( $dismissal_key, $this->user_id ) );
-		$this->assertEmpty( get_user_meta( $this->user_id, $dismissal_key, true ) );
+		$this->assertSame( 'seen', \get_user_option( $dismissal_key, $this->user_id ) );
+		$this->assertEmpty( \get_user_meta( $this->user_id, $dismissal_key, true ) );
 	}
 
 	/**
@@ -657,8 +657,8 @@ public function test_restore_notification_clears_user_meta() {
 		$dismissal_key = $notification->get_dismissal_key();
 
 		// Set notification dismissed in both user option and old user meta way.
-		update_user_option( $this->user_id, $dismissal_key, 'seen' );
-		update_user_meta( $this->user_id, $dismissal_key, 'seen' );
+		\update_user_option( $this->user_id, $dismissal_key, 'seen' );
+		\update_user_meta( $this->user_id, $dismissal_key, 'seen' );
 
 		$this->assertTrue( Yoast_Notification_Center::restore_notification( $notification ) );
 	}
@@ -684,7 +684,7 @@ public function test_retrieve_notifications_from_storage_strips_nonces() {
 			$expected[ $sample_notification->get_id() ] = null;
 		}
 
-		update_user_option( get_current_user_id(), Yoast_Notification_Center::STORAGE_KEY, $storage_data );
+		\update_user_option( \get_current_user_id(), Yoast_Notification_Center::STORAGE_KEY, $storage_data );
 
 		$notification_center->setup_current_notifications();
 
@@ -693,7 +693,7 @@ public function test_retrieve_notifications_from_storage_strips_nonces() {
 			$stored_notifications[ $index ] = $stored_notification->to_array();
 		}
 
-		$this->assertSame( $expected, wp_list_pluck( wp_list_pluck( $stored_notifications, 'options' ), 'nonce', 'id' ) );
+		$this->assertSame( $expected, \wp_list_pluck( \wp_list_pluck( $stored_notifications, 'options' ), 'nonce', 'id' ) );
 	}
 
 	/**
@@ -704,10 +704,10 @@ public function test_retrieve_notifications_from_storage_strips_nonces() {
 	public function test_update_storage_strips_nonces() {
 		$notification_center = Yoast_Notification_Center::get();
 
-		add_filter( 'yoast_notifications_before_storage', [ $this, 'get_sample_notifications' ] );
+		\add_filter( 'yoast_notifications_before_storage', [ $this, 'get_sample_notifications' ] );
 		$notification_center->update_storage();
 
-		$stored_notifications = get_user_option( Yoast_Notification_Center::STORAGE_KEY, get_current_user_id() );
+		$stored_notifications = \get_user_option( Yoast_Notification_Center::STORAGE_KEY, \get_current_user_id() );
 
 		$expected             = [];
 		$sample_notifications = $this->get_sample_notifications();
@@ -715,7 +715,7 @@ public function test_update_storage_strips_nonces() {
 			$expected[ $sample_notification->get_id() ] = null;
 		}
 
-		$this->assertSame( $expected, wp_list_pluck( wp_list_pluck( $stored_notifications, 'options' ), 'nonce', 'id' ) );
+		$this->assertSame( $expected, \wp_list_pluck( \wp_list_pluck( $stored_notifications, 'options' ), 'nonce', 'id' ) );
 	}
 
 	/**
@@ -725,7 +725,7 @@ public function test_update_storage_strips_nonces() {
 	 */
 	public function test_remove_notification_by_id_when_no_notification_is_found() {
 		$notification_center = $this
-			->getMockBuilder( 'Yoast_Notification_Center' )
+			->getMockBuilder( Yoast_Notification_Center::class )
 			->disableOriginalConstructor()
 			->setMethods( [ 'remove_notification' ] )
 			->getMock();
@@ -744,7 +744,7 @@ public function test_remove_notification_by_id_when_no_notification_is_found() {
 	 */
 	public function test_remove_notification_by_id_when_notification_is_found() {
 		$notification_center = $this
-			->getMockBuilder( 'Yoast_Notification_Center' )
+			->getMockBuilder( Yoast_Notification_Center::class )
 			->disableOriginalConstructor()
 			->setMethods( [ 'remove_notification', 'get_notification_by_id' ] )
 			->getMock();
diff --git a/tests/WP/Notifications/test-class-yoast-notification.php b/tests/WP/Notifications/Yoast_Notification_Test.php
similarity index 95%
rename from tests/WP/Notifications/test-class-yoast-notification.php
rename to tests/WP/Notifications/Yoast_Notification_Test.php
index 769778edae7..609532ea539 100644
--- a/tests/WP/Notifications/test-class-yoast-notification.php
+++ b/tests/WP/Notifications/Yoast_Notification_Test.php
@@ -1,11 +1,10 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package Yoast\Tests\Notifications
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Notifications;
+
+use WPSEO_Utils;
 use Yoast\WP\SEO\Tests\WP\TestCase;
+use Yoast_Notification;
 
 /**
  * Class Yoast_Notification_Test.
@@ -37,7 +36,7 @@ public function set_up() {
 		$user = $this->factory->user->create_and_get();
 		$user->add_cap( 'wpseo_manage_options' );
 
-		wp_set_current_user( $user->ID );
+		\wp_set_current_user( $user->ID );
 	}
 
 	/**
@@ -54,7 +53,7 @@ public function test_not_persistent() {
 	public function test_set_defaults() {
 		$subject = new Yoast_Notification( 'message', [] );
 		$test    = $subject->to_array();
-		$user    = wp_get_current_user();
+		$user    = \wp_get_current_user();
 
 		$this->assertEquals(
 			[
@@ -100,7 +99,7 @@ public function test_nonce() {
 	public function test_nonce_not_set() {
 		$subject = new Yoast_Notification( 'message', [ 'id' => 'id' ] );
 		$nonce   = $subject->get_nonce();
-		$this->assertTrue( wp_verify_nonce( $nonce, 'id' ) !== false );
+		$this->assertTrue( \wp_verify_nonce( $nonce, 'id' ) !== false );
 	}
 
 	/**
@@ -306,7 +305,7 @@ public function add_wpseo_notification_capabilities( $current_capabilities = []
 	 * @param string $capability Capability to add.
 	 */
 	private function add_cap( $capability ) {
-		$me = wp_get_current_user();
+		$me = \wp_get_current_user();
 		if ( ! empty( $me ) ) {
 			$me->add_cap( $capability );
 		}
@@ -318,7 +317,7 @@ private function add_cap( $capability ) {
 	 * @param string $capability Capability to remove.
 	 */
 	private function remove_cap( $capability ) {
-		$me = wp_get_current_user();
+		$me = \wp_get_current_user();
 		if ( ! empty( $me ) ) {
 			$me->remove_cap( $capability );
 		}
diff --git a/tests/WP/Notifiers/test-class-dismissible-notification.php b/tests/WP/Notifiers/Dismissible_Notification_Test.php
similarity index 94%
rename from tests/WP/Notifiers/test-class-dismissible-notification.php
rename to tests/WP/Notifiers/Dismissible_Notification_Test.php
index 3be20b8c4d0..6ab5fe43987 100644
--- a/tests/WP/Notifiers/test-class-dismissible-notification.php
+++ b/tests/WP/Notifiers/Dismissible_Notification_Test.php
@@ -1,19 +1,17 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Notifiers
- */
+
+namespace Yoast\WP\SEO\Tests\WP\Notifiers;
 
 use Yoast\WP\SEO\Tests\WP\Doubles\Admin\Dismissible_Notification_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
+use Yoast_Notification_Center;
 
 /**
  * Unit Test Class.
  *
  * @group notifiers
  */
-class WPSEO_Dismissible_Notification_Test extends TestCase {
+class Dismissible_Notification_Test extends TestCase {
 
 	/**
 	 * Tests the listen method when required value is not present in the request URL.
@@ -64,7 +62,7 @@ public function test_listen_when_notification_will_be_dismissed() {
 	 */
 	public function test_handle_where_situation_is_applicable() {
 		$notification_center = $this
-			->getMockBuilder( 'Yoast_Notification_Center' )
+			->getMockBuilder( Yoast_Notification_Center::class )
 			->disableOriginalConstructor()
 			->setMethods( [ 'add_notification' ] )
 			->getMock();
@@ -93,7 +91,7 @@ public function test_handle_where_situation_is_applicable() {
 	 */
 	public function test_handle_where_situation_is_not_applicable() {
 		$notification_center = $this
-			->getMockBuilder( 'Yoast_Notification_Center' )
+			->getMockBuilder( Yoast_Notification_Center::class )
 			->disableOriginalConstructor()
 			->setMethods( [ 'remove_notification_by_id' ] )
 			->getMock();
diff --git a/tests/WP/Repositories/test-class-seo-links-repository.php b/tests/WP/Repositories/SEO_Links_Repository_Test.php
similarity index 99%
rename from tests/WP/Repositories/test-class-seo-links-repository.php
rename to tests/WP/Repositories/SEO_Links_Repository_Test.php
index 99b2d0d931a..8f135fb4c30 100644
--- a/tests/WP/Repositories/test-class-seo-links-repository.php
+++ b/tests/WP/Repositories/SEO_Links_Repository_Test.php
@@ -1,9 +1,6 @@
 <?php
-/**
- * WPSEO plugin integration test file.
- *
- * @package Yoast\Tests\Repositories
- */
+
+namespace Yoast\WP\SEO\Tests\WP\Repositories;
 
 use Yoast\WP\SEO\Models\SEO_Links;
 use Yoast\WP\SEO\Repositories\SEO_Links_Repository;
@@ -545,7 +542,7 @@ public function test_delete_many_by_id( $ids, $expected_result ) {
 
 		$result = $this->instance->delete_many_by_id( $ids );
 
-		$in = implode( ',', $ids );
+		$in = \implode( ',', $ids );
 
 		$db = $wpdb->get_var( $wpdb->prepare( 'SELECT COUNT(*) FROM `' . $wpdb->prefix . 'yoast_seo_links` WHERE `id`IN (%s)', $in ) );
 
diff --git a/tests/WP/Sitemaps/test-class-wpseo-author-sitemap-provider.php b/tests/WP/Sitemaps/Author_Sitemap_Provider_Test.php
similarity index 89%
rename from tests/WP/Sitemaps/test-class-wpseo-author-sitemap-provider.php
rename to tests/WP/Sitemaps/Author_Sitemap_Provider_Test.php
index 41906786105..e9516e5e26b 100644
--- a/tests/WP/Sitemaps/test-class-wpseo-author-sitemap-provider.php
+++ b/tests/WP/Sitemaps/Author_Sitemap_Provider_Test.php
@@ -1,19 +1,19 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Sitemaps
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Sitemaps;
+
+use OutOfBoundsException;
+use WPSEO_Author_Sitemap_Provider;
+use WPSEO_Options;
 use Yoast\WP\SEO\Tests\WP\Doubles\Inc\Sitemaps_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
- * Class WPSEO_Author_Sitemap_Provider_Test.
+ * Class Author_Sitemap_Provider_Test.
  *
  * @group sitemaps
  */
-class WPSEO_Author_Sitemap_Provider_Test extends TestCase {
+class Author_Sitemap_Provider_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
@@ -77,7 +77,7 @@ public function test_author_not_excluded_from_sitemap_non_zero_posts() {
 		$this->assertCount( 1, $sitemap_links );
 
 		// Makes sure it's the user we expected.
-		$this->assertContains( get_author_posts_url( $user_id ), wp_list_pluck( $sitemap_links, 'loc' ) );
+		$this->assertContains( \get_author_posts_url( $user_id ), \wp_list_pluck( $sitemap_links, 'loc' ) );
 	}
 
 	/**
@@ -101,10 +101,10 @@ public function test_author_not_excluded_from_sitemap_by_zero_posts() {
 		$this->assertCount( 3, $sitemap_links );
 
 		// Makes sure it are the users we expected.
-		$sitemap_urls = wp_list_pluck( $sitemap_links, 'loc' );
-		$this->assertContains( get_author_posts_url( $author_id ), $sitemap_urls );
-		$this->assertContains( get_author_posts_url( $admin_id ), $sitemap_urls );
-		$this->assertContains( get_author_posts_url( $editor_id ), $sitemap_urls );
+		$sitemap_urls = \wp_list_pluck( $sitemap_links, 'loc' );
+		$this->assertContains( \get_author_posts_url( $author_id ), $sitemap_urls );
+		$this->assertContains( \get_author_posts_url( $admin_id ), $sitemap_urls );
+		$this->assertContains( \get_author_posts_url( $editor_id ), $sitemap_urls );
 	}
 
 	/**
@@ -123,7 +123,7 @@ public function test_author_exclusion() {
 		$this->factory->post->create_many( 3, [ 'post_author' => $user_id ] );
 
 		// Excludes the user from the sitemaps.
-		update_user_meta( $user_id, 'wpseo_noindex_author', 'on' );
+		\update_user_meta( $user_id, 'wpseo_noindex_author', 'on' );
 
 		// Checks which authors are in the sitemap, there should be none.
 		self::$class_instance->get_sitemap_links( 'author', 10, 1 );
@@ -142,10 +142,10 @@ public function test_get_index_links_empty_sitemap() {
 		WPSEO_Options::set( 'disable-author', false );
 
 		// Fetches the global sitemap.
-		set_query_var( 'sitemap', 'author' );
+		\set_query_var( 'sitemap', 'author' );
 
 		// Sets the page to the second one, which should not contain an entry, and should not exist.
-		set_query_var( 'sitemap_n', '2' );
+		\set_query_var( 'sitemap_n', '2' );
 
 		// Loads the sitemap.
 		$sitemaps = new Sitemaps_Double();
@@ -165,7 +165,7 @@ public function test_get_index_links_disabled_archive() {
 		WPSEO_Options::set( 'disable-author', true );
 
 		// Fetches the global sitemap.
-		set_query_var( 'sitemap', 'author' );
+		\set_query_var( 'sitemap', 'author' );
 
 		// Loads the sitemap.
 		$sitemaps = new Sitemaps_Double();
diff --git a/tests/WP/Sitemaps/test-class-wpseo-sitemaps-cache-data.php b/tests/WP/Sitemaps/Cache_Data_Test.php
similarity index 94%
rename from tests/WP/Sitemaps/test-class-wpseo-sitemaps-cache-data.php
rename to tests/WP/Sitemaps/Cache_Data_Test.php
index 040cd463338..eb43de5ea8b 100644
--- a/tests/WP/Sitemaps/test-class-wpseo-sitemaps-cache-data.php
+++ b/tests/WP/Sitemaps/Cache_Data_Test.php
@@ -1,18 +1,18 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Sitemaps
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Sitemaps;
+
+use stdClass;
+use WPSEO_Sitemap_Cache_Data;
+use WPSEO_Sitemap_Cache_Data_Interface;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
- * Class WPSEO_Sitemaps_Test.
+ * Class Cache_Data_Test.
  *
  * @group sitemaps
  */
-class WPSEO_Sitemaps_Cache_Data_Test extends TestCase {
+class Cache_Data_Test extends TestCase {
 
 	/**
 	 * Subject to test against.
@@ -160,9 +160,9 @@ public function test_serialize_unserialize() {
 		$this->subject->set_sitemap( $sitemap );
 
 		// phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.serialize_serialize -- Reason: There's no way for user input to get in between serialize and unserialize.
-		$tmp = serialize( $this->subject );
+		$tmp = \serialize( $this->subject );
 		// phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.serialize_unserialize -- Reason: There's no way for user input to get in between serialize and unserialize.
-		$test = unserialize( $tmp );
+		$test = \unserialize( $tmp );
 
 		$this->assertEquals( $this->subject, $test );
 	}
diff --git a/tests/WP/Sitemaps/test-class-wpseo-sitemaps-cache.php b/tests/WP/Sitemaps/Cache_Test.php
similarity index 87%
rename from tests/WP/Sitemaps/test-class-wpseo-sitemaps-cache.php
rename to tests/WP/Sitemaps/Cache_Test.php
index 7385f98e153..5e9ebc644aa 100644
--- a/tests/WP/Sitemaps/test-class-wpseo-sitemaps-cache.php
+++ b/tests/WP/Sitemaps/Cache_Test.php
@@ -1,24 +1,24 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Sitemaps
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Sitemaps;
+
+use WPSEO_Sitemap_Cache_Data;
+use WPSEO_Sitemaps_Cache;
+use WPSEO_Sitemaps_Cache_Validator;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
- * Class WPSEO_Sitemaps_Cache_Test.
+ * Class Cache_Test.
  *
  * @group sitemaps
  */
-class WPSEO_Sitemaps_Cache_Test extends TestCase {
+class Cache_Test extends TestCase {
 
 	/**
 	 * Clean up.
 	 */
 	public function tear_down() {
-		remove_action( 'update_option', [ 'WPSEO_Sitemaps_Cache', 'clear_on_option_update' ] );
+		\remove_action( 'update_option', [ WPSEO_Sitemaps_Cache::class, 'clear_on_option_update' ] );
 
 		parent::tear_down();
 	}
@@ -63,9 +63,9 @@ public function test_transient_cache_data_object() {
 		 * to do so ourselves.
 		 * As of PHP 7.4, the new serialization using magic methods is used.
 		 */
-		if ( PHP_VERSION_ID < 70400 ) {
+		if ( \PHP_VERSION_ID < 70400 ) {
 			// phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.serialize_unserialize -- Reason: There's no security risk, because users don't interact with tests.
-			$result = unserialize( $result );
+			$result = \unserialize( $result );
 		}
 
 		$this->assertEquals( $test, $result );
@@ -88,12 +88,12 @@ public function test_transient_string_to_cache_data() {
 
 		$transient_key = WPSEO_Sitemaps_Cache_Validator::get_storage_key( $type, $page );
 
-		set_transient( $transient_key, $sitemap, DAY_IN_SECONDS );
+		\set_transient( $transient_key, $sitemap, \DAY_IN_SECONDS );
 
 		$cache  = new WPSEO_Sitemaps_Cache();
 		$result = $cache->get_sitemap_data( $type, $page );
 
-		$this->assertEquals( $sitemap, get_transient( $transient_key ) );
+		$this->assertEquals( $sitemap, \get_transient( $transient_key ) );
 		$this->assertNull( $result );
 	}
 
@@ -120,18 +120,18 @@ public function test_retrieving_transient_stored_in_php_lt_74() {
 		 * These functions are used in the get_sitemap[_data]() method to retrieve the transient.
 		 * This filter short-circuits those function calls to return the specific value we need for this test.
 		 */
-		add_filter(
+		\add_filter(
 			"pre_transient_{$transient_key}",
 			static function ( $pre_transient ) {
 				$pre_transient = 'C:24:"WPSEO_Sitemap_Cache_Data":107:{a:2:{s:6:"status";s:2:"ok";s:3:"xml";s:61:"this is a wpseo_sitemap_cache_data object stored in PHP < 7.4";}}';
-				return maybe_unserialize( $pre_transient );
+				return \maybe_unserialize( $pre_transient );
 			}
 		);
 
 		$cache  = new WPSEO_Sitemaps_Cache();
 		$result = $cache->get_sitemap_data( $type, $page );
 
-		$this->assertInstanceOf( 'WPSEO_Sitemap_Cache_Data', $result );
+		$this->assertInstanceOf( WPSEO_Sitemap_Cache_Data::class, $result );
 		$this->assertSame( $sitemap, $result->get_sitemap() );
 		$this->assertSame( 'ok', $result->get_status() );
 	}
@@ -167,20 +167,20 @@ public function test_retrieving_transient_stored_in_php_gte_74() {
 		 * These functions are used in the get_sitemap[_data]() method to retrieve the transient.
 		 * This filter short-circuits those function calls to return the specific value we need for this test.
 		 */
-		add_filter(
+		\add_filter(
 			"pre_transient_{$transient_key}",
 			static function ( $pre_transient ) {
 				$pre_transient = 'O:24:"WPSEO_Sitemap_Cache_Data":2:{s:6:"status";s:2:"ok";s:3:"xml";s:62:"this is a wpseo_sitemap_cache_data object stored in PHP >= 7.4";}';
-				return maybe_unserialize( $pre_transient );
+				return \maybe_unserialize( $pre_transient );
 			}
 		);
 
 		$cache  = new WPSEO_Sitemaps_Cache();
 		$result = $cache->get_sitemap_data( $type, $page );
 
-		if ( PHP_VERSION_ID >= 70400 ) {
+		if ( \PHP_VERSION_ID >= 70400 ) {
 			// PHP 7.4+.
-			$this->assertInstanceOf( 'WPSEO_Sitemap_Cache_Data', $result );
+			$this->assertInstanceOf( WPSEO_Sitemap_Cache_Data::class, $result );
 			$this->assertSame( $sitemap, $result->get_sitemap() );
 			$this->assertSame( 'ok', $result->get_status() );
 		}
@@ -203,14 +203,14 @@ public function test_clear() {
 		$test_content = 'test_content';
 
 		$cache_key = WPSEO_Sitemaps_Cache_Validator::get_storage_key( $type, $page );
-		set_transient( $cache_key, $test_content );
+		\set_transient( $cache_key, $test_content );
 
 		// Act.
 		WPSEO_Sitemaps_Cache::clear();
 		WPSEO_Sitemaps_Cache::clear_queued();
 
 		$cache_key = WPSEO_Sitemaps_Cache_Validator::get_storage_key( $type, $page );
-		$content   = get_transient( $cache_key );
+		$content   = \get_transient( $cache_key );
 
 		// Assert.
 		$this->assertEquals( $test_content, $content );
@@ -229,7 +229,7 @@ public function test_clear_type() {
 		$test_content = 'test_content';
 
 		$cache_key = WPSEO_Sitemaps_Cache_Validator::get_storage_key( $type, $page );
-		set_transient( $cache_key, $test_content );
+		\set_transient( $cache_key, $test_content );
 
 		// Act.
 		WPSEO_Sitemaps_Cache::clear( [ $type ] );
@@ -237,7 +237,7 @@ public function test_clear_type() {
 
 		// Get the key again.
 		$cache_key = WPSEO_Sitemaps_Cache_Validator::get_storage_key( $type, $page );
-		$result    = get_transient( $cache_key );
+		$result    = \get_transient( $cache_key );
 
 		// Assert.
 		$this->assertEquals( $test_content, $result );
@@ -254,14 +254,14 @@ public function test_clear_index_also_cleared() {
 		$test_index_content = 'test_content';
 
 		$index_cache_key = WPSEO_Sitemaps_Cache_Validator::get_storage_key();
-		set_transient( $index_cache_key, $test_index_content );
+		\set_transient( $index_cache_key, $test_index_content );
 
 		/*
 		 * The cache invalidator is based on time so if there isn't enough time
 		 * difference between the two generations we will end up with the same
 		 * cache invalidator, failing this test.
 		 */
-		usleep( 10000 );
+		\usleep( 10000 );
 
 		// Act.
 		WPSEO_Sitemaps_Cache::clear( [ 'page' ] );
@@ -269,7 +269,7 @@ public function test_clear_index_also_cleared() {
 
 		// Get the key again.
 		$index_cache_key = WPSEO_Sitemaps_Cache_Validator::get_storage_key();
-		$result          = get_transient( $index_cache_key );
+		$result          = \get_transient( $index_cache_key );
 
 		// Assert.
 		$this->assertEquals( $test_index_content, $result );
@@ -290,10 +290,10 @@ public function test_clear_type_isolation() {
 		$type_b_content = 'content_b';
 
 		$type_a_key = WPSEO_Sitemaps_Cache_Validator::get_storage_key( $type_a );
-		set_transient( $type_a_key, $type_a_content );
+		\set_transient( $type_a_key, $type_a_content );
 
 		$type_b_key = WPSEO_Sitemaps_Cache_Validator::get_storage_key( $type_b );
-		set_transient( $type_b_key, $type_b_content );
+		\set_transient( $type_b_key, $type_b_content );
 
 		// Act.
 		WPSEO_Sitemaps_Cache::clear( [ $type_a ] );
@@ -301,7 +301,7 @@ public function test_clear_type_isolation() {
 
 		// Get the key again.
 		$type_b_key = WPSEO_Sitemaps_Cache_Validator::get_storage_key( $type_b );
-		$result     = get_transient( $type_b_key );
+		$result     = \get_transient( $type_b_key );
 
 		// Assert.
 		$this->assertEquals( $type_b_content, $result );
@@ -316,9 +316,9 @@ public function test_register_clear_on_option_update() {
 
 		new WPSEO_Sitemaps_Cache();
 		// Hook will be added on default priority.
-		$has_action = has_action(
+		$has_action = \has_action(
 			'update_option',
-			[ 'WPSEO_Sitemaps_Cache', 'clear_on_option_update' ]
+			[ WPSEO_Sitemaps_Cache::class, 'clear_on_option_update' ]
 		);
 		$this->assertEquals( 10, $has_action );
 	}
@@ -340,16 +340,16 @@ public function test_clear_transient_cache() {
 		WPSEO_Sitemaps_Cache::register_clear_on_option_update( $option, $type );
 
 		$cache_key = WPSEO_Sitemaps_Cache_Validator::get_storage_key( $type, $page );
-		set_transient( $cache_key, $test_content );
+		\set_transient( $cache_key, $test_content );
 
 		// Act.
 		// Updating the option should clear cache for specified type.
-		do_action( 'update_option', $option );
+		\do_action( 'update_option', $option );
 		WPSEO_Sitemaps_Cache::clear_queued();
 
 		// Get the key again.
 		$cache_key = WPSEO_Sitemaps_Cache_Validator::get_storage_key( $type, $page );
-		$result    = get_transient( $cache_key );
+		$result    = \get_transient( $cache_key );
 
 		// Assert.
 		$this->assertEquals( $test_content, $result );
diff --git a/tests/WP/Sitemaps/test-class-wpseo-sitemaps-cache-validator.php b/tests/WP/Sitemaps/Cache_Validator_Test.php
similarity index 86%
rename from tests/WP/Sitemaps/test-class-wpseo-sitemaps-cache-validator.php
rename to tests/WP/Sitemaps/Cache_Validator_Test.php
index 36d8be7460d..849d9e2df11 100644
--- a/tests/WP/Sitemaps/test-class-wpseo-sitemaps-cache-validator.php
+++ b/tests/WP/Sitemaps/Cache_Validator_Test.php
@@ -1,20 +1,19 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Sitemaps
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Sitemaps;
+
+use InvalidArgumentException;
+use WPSEO_Sitemaps_Cache_Validator;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
- * Class WPSEO_Sitemaps_Cache_Validator_Test.
+ * Class Cache_Validator_Test.
  *
  * @coversDefaultClass WPSEO_Sitemaps_Cache_Validator
  *
  * @group sitemaps
  */
-class WPSEO_Sitemaps_Cache_Validator_Test extends TestCase {
+class Cache_Validator_Test extends TestCase {
 
 	/**
 	 * Test the building of cache keys.
@@ -36,7 +35,7 @@ public function test_get_validator_key_global() {
 	public function test_get_validator_key_type() {
 
 		$type     = 'blabla';
-		$expected = sprintf( WPSEO_Sitemaps_Cache_Validator::VALIDATION_TYPE_KEY_FORMAT, $type );
+		$expected = \sprintf( WPSEO_Sitemaps_Cache_Validator::VALIDATION_TYPE_KEY_FORMAT, $type );
 
 		$result = WPSEO_Sitemaps_Cache_Validator::get_validator_key( $type );
 
@@ -56,10 +55,10 @@ public function test_get_storage_key() {
 		$type_validator   = 'type';
 
 		$global_validator_key = WPSEO_Sitemaps_Cache_Validator::get_validator_key();
-		update_option( $global_validator_key, $global_validator );
+		\update_option( $global_validator_key, $global_validator );
 
 		$type_validator_key = WPSEO_Sitemaps_Cache_Validator::get_validator_key( $type );
-		update_option( $type_validator_key, $type_validator );
+		\update_option( $type_validator_key, $type_validator );
 
 		$prefix  = WPSEO_Sitemaps_Cache_Validator::STORAGE_KEY_PREFIX;
 		$postfix = '_1:global_type';
@@ -84,13 +83,13 @@ public function test_get_storage_key() {
 	public function test_get_storage_key_very_long_type() {
 
 		$page = 1;
-		$type = str_repeat( 'a', 60 );
+		$type = \str_repeat( 'a', 60 );
 
 		// Act.
 		$result = WPSEO_Sitemaps_Cache_Validator::get_storage_key( $type, $page );
 
 		// Assert.
-		$this->assertEquals( 45, strlen( $result ) );
+		$this->assertEquals( 45, \strlen( $result ) );
 	}
 
 	/**
diff --git a/tests/WP/Sitemaps/test-class-wpseo-sitemap-image-parser.php b/tests/WP/Sitemaps/Image_Parser_Test.php
similarity index 89%
rename from tests/WP/Sitemaps/test-class-wpseo-sitemap-image-parser.php
rename to tests/WP/Sitemaps/Image_Parser_Test.php
index 4b350f48762..6a958db9490 100644
--- a/tests/WP/Sitemaps/test-class-wpseo-sitemap-image-parser.php
+++ b/tests/WP/Sitemaps/Image_Parser_Test.php
@@ -1,19 +1,17 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Sitemaps
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Sitemaps;
+
+use WPSEO_Sitemap_Image_Parser;
 use Yoast\WP\SEO\Tests\WP\Doubles\Inc\Sitemap_Image_Parser_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
- * Class WPSEO_Sitemap_Image_Parser_Test.
+ * Class Image_Parser_Test.
  *
  * @group sitemaps
  */
-class WPSEO_Sitemap_Image_Parser_Test extends TestCase {
+class Image_Parser_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
@@ -43,7 +41,7 @@ public function test_get_images() {
 			[ 'post_content' => "<img src='{$content_src}' alt='jibberish' />" ]
 		);
 
-		$images = self::$class_instance->get_images( get_post( $post_id ) );
+		$images = self::$class_instance->get_images( \get_post( $post_id ) );
 		$this->assertNotEmpty( $images[0] );
 		$content_image = $images[0];
 		$this->assertEquals( $content_src, $content_image['src'] );
diff --git a/tests/WP/Sitemaps/test-class-wpseo-post-type-sitemap-provider.php b/tests/WP/Sitemaps/Post_Type_Sitemap_Provider_Test.php
similarity index 75%
rename from tests/WP/Sitemaps/test-class-wpseo-post-type-sitemap-provider.php
rename to tests/WP/Sitemaps/Post_Type_Sitemap_Provider_Test.php
index 6c8f030172b..a32b4e33f4b 100644
--- a/tests/WP/Sitemaps/test-class-wpseo-post-type-sitemap-provider.php
+++ b/tests/WP/Sitemaps/Post_Type_Sitemap_Provider_Test.php
@@ -1,21 +1,20 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Sitemaps
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Sitemaps;
+
+use WPSEO_Options;
+use WPSEO_Post_Type_Sitemap_Provider;
 use Yoast\WP\SEO\Tests\WP\Doubles\Inc\Post_Type_Sitemap_Provider_Double;
 use Yoast\WP\SEO\Tests\WP\Doubles\Inc\Sitemaps_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
- * Class WPSEO_Post_Type_Sitemap_Provider_Test.
+ * Class Post_Type_Sitemap_Provider_Test.
  *
  * @group sitemaps
  * @coversDefaultClass \Yoast\WP\SEO\Models\SEO_Links\WPSEO_Post_Type_Sitemap_Provider
  */
-class WPSEO_Post_Type_Sitemap_Provider_Test extends TestCase {
+class Post_Type_Sitemap_Provider_Test extends TestCase {
 
 	/**
 	 * Sitemap Provider instance.
@@ -95,14 +94,14 @@ public function test_get_index_links_empty_bucket() {
 		$this->excluded_posts = [ $this->factory->post->create() ]; // Remove this post.
 		$this->factory->post->create();
 
-		add_filter( 'wpseo_exclude_from_sitemap_by_post_ids', [ $this, 'exclude_post' ] );
-		add_filter( 'wpseo_sitemap_entries_per_page', [ $this, 'return_one' ] );
+		\add_filter( 'wpseo_exclude_from_sitemap_by_post_ids', [ $this, 'exclude_post' ] );
+		\add_filter( 'wpseo_sitemap_entries_per_page', [ $this, 'return_one' ] );
 
 		// Fetch the global sitemap.
-		set_query_var( 'sitemap', 'post' );
+		\set_query_var( 'sitemap', 'post' );
 
 		// Set the page to the second one, which should not contain an entry, but should exist.
-		set_query_var( 'sitemap_n', '2' );
+		\set_query_var( 'sitemap_n', '2' );
 
 		// Load the sitemap.
 		$sitemaps = new Sitemaps_Double();
@@ -114,7 +113,7 @@ public function test_get_index_links_empty_bucket() {
 		);
 
 		// Remove the filter.
-		remove_filter( 'wpseo_exclude_from_sitemap_by_post_ids', [ $this, 'exclude_post' ] );
+		\remove_filter( 'wpseo_exclude_from_sitemap_by_post_ids', [ $this, 'exclude_post' ] );
 	}
 
 	/**
@@ -124,10 +123,10 @@ public function test_get_index_links_empty_bucket() {
 	 */
 	public function test_get_index_links_empty_sitemap() {
 		// Fetch the global sitemap.
-		set_query_var( 'sitemap', 'post' );
+		\set_query_var( 'sitemap', 'post' );
 
 		// Set the page to the second one, which should not contain an entry, and should not exist.
-		set_query_var( 'sitemap_n', '2' );
+		\set_query_var( 'sitemap_n', '2' );
 
 		// Load the sitemap.
 		$sitemaps = new Sitemaps_Double();
@@ -145,51 +144,51 @@ public function test_get_index_links_empty_sitemap() {
 	public function test_get_sitemap_links() {
 		$sitemap_provider = new Post_Type_Sitemap_Provider_Double();
 
-		$current_show_on_front  = get_option( 'show_on_front' );
-		$current_page_on_front  = (int) get_option( 'page_on_front' );
-		$current_page_for_posts = (int) get_option( 'page_for_posts' );
+		$current_show_on_front  = \get_option( 'show_on_front' );
+		$current_page_on_front  = (int) \get_option( 'page_on_front' );
+		$current_page_for_posts = (int) \get_option( 'page_for_posts' );
 
 		$front_page = $this->factory()->post->create_and_get( [ 'post_type' => 'page' ] );
 		$posts_page = $this->factory()->post->create_and_get( [ 'post_type' => 'page' ] );
 		$post_id    = $this->factory()->post->create_and_get( [ 'post_type' => 'post' ] );
 
-		update_option( 'show_on_front', 'page' );
-		update_option( 'page_on_front', $front_page->ID );
-		update_option( 'page_for_posts', 0 );
+		\update_option( 'show_on_front', 'page' );
+		\update_option( 'page_on_front', $front_page->ID );
+		\update_option( 'page_for_posts', 0 );
 
 		$sitemap_links = $sitemap_provider->get_sitemap_links( 'page', 1, 1 );
-		$this->assertContains( get_permalink( $front_page->ID ), $sitemap_links[0] );
+		$this->assertContains( \get_permalink( $front_page->ID ), $sitemap_links[0] );
 
 		$sitemap_links = $sitemap_provider->get_sitemap_links( 'post', 1, 1 );
-		$this->assertContains( get_permalink( $post_id ), $sitemap_links[0] );
+		$this->assertContains( \get_permalink( $post_id ), $sitemap_links[0] );
 
-		update_option( 'show_on_front', 'page' );
-		update_option( 'page_on_front', $front_page->ID );
-		update_option( 'page_for_posts', $posts_page->ID );
+		\update_option( 'show_on_front', 'page' );
+		\update_option( 'page_on_front', $front_page->ID );
+		\update_option( 'page_for_posts', $posts_page->ID );
 
 		$sitemap_links = $sitemap_provider->get_sitemap_links( 'page', 1, 1 );
-		$this->assertContains( YoastSEO()->helpers->url->home(), $sitemap_links[0] );
-		$this->assertContains( get_permalink( $front_page->ID ), $sitemap_links[0] );
+		$this->assertContains( \YoastSEO()->helpers->url->home(), $sitemap_links[0] );
+		$this->assertContains( \get_permalink( $front_page->ID ), $sitemap_links[0] );
 
 		$sitemap_links = $sitemap_provider->get_sitemap_links( 'post', 2, 1 );
-		$this->assertContains( get_post_type_archive_link( 'post' ), $sitemap_links[0] );
-		$this->assertContains( get_permalink( $posts_page->ID ), $sitemap_links[0] );
-		$this->assertContains( get_permalink( $post_id ), $sitemap_links[1] );
+		$this->assertContains( \get_post_type_archive_link( 'post' ), $sitemap_links[0] );
+		$this->assertContains( \get_permalink( $posts_page->ID ), $sitemap_links[0] );
+		$this->assertContains( \get_permalink( $post_id ), $sitemap_links[1] );
 
-		update_option( 'show_on_front', 'posts' );
-		update_option( 'page_on_front', 0 );
-		update_option( 'page_for_posts', 0 );
+		\update_option( 'show_on_front', 'posts' );
+		\update_option( 'page_on_front', 0 );
+		\update_option( 'page_for_posts', 0 );
 
 		$sitemap_links = $sitemap_provider->get_sitemap_links( 'page', 1, 1 );
-		$this->assertContains( YoastSEO()->helpers->url->home(), $sitemap_links[0] );
+		$this->assertContains( \YoastSEO()->helpers->url->home(), $sitemap_links[0] );
 
 		$sitemap_links = $sitemap_provider->get_sitemap_links( 'post', 2, 1 );
-		$this->assertContains( YoastSEO()->helpers->url->home(), $sitemap_links[0] );
-		$this->assertContains( get_permalink( $post_id ), $sitemap_links[1] );
+		$this->assertContains( \YoastSEO()->helpers->url->home(), $sitemap_links[0] );
+		$this->assertContains( \get_permalink( $post_id ), $sitemap_links[1] );
 
-		update_option( 'show_on_front', $current_show_on_front );
-		update_option( 'page_for_posts', $current_page_for_posts );
-		update_option( 'page_on_front', $current_page_on_front );
+		\update_option( 'show_on_front', $current_show_on_front );
+		\update_option( 'page_for_posts', $current_page_for_posts );
+		\update_option( 'page_on_front', $current_page_on_front );
 	}
 
 	/**
@@ -200,7 +199,7 @@ public function test_get_sitemap_links() {
 	public function test_get_excluded_posts_with_set_filter() {
 		$sitemap_provider = new Post_Type_Sitemap_Provider_Double();
 
-		add_filter( 'wpseo_exclude_from_sitemap_by_post_ids', [ $this, 'filter_with_output' ] );
+		\add_filter( 'wpseo_exclude_from_sitemap_by_post_ids', [ $this, 'filter_with_output' ] );
 
 		$expected = [
 			0 => 5,
@@ -212,7 +211,7 @@ public function test_get_excluded_posts_with_set_filter() {
 
 		$this->assertEquals( $expected, $sitemap_provider->get_excluded_posts( 'post' ) );
 
-		remove_filter( 'wpseo_exclude_from_sitemap_by_post_ids', [ $this, 'filter_with_output' ] );
+		\remove_filter( 'wpseo_exclude_from_sitemap_by_post_ids', [ $this, 'filter_with_output' ] );
 	}
 
 	/**
@@ -223,11 +222,11 @@ public function test_get_excluded_posts_with_set_filter() {
 	public function test_get_excluded_posts_with_set_filter_that_has_invalid_return_value() {
 		$sitemap_provider = new Post_Type_Sitemap_Provider_Double();
 
-		add_filter( 'wpseo_exclude_from_sitemap_by_post_ids', [ $this, 'filter_with_invalid_output' ] );
+		\add_filter( 'wpseo_exclude_from_sitemap_by_post_ids', [ $this, 'filter_with_invalid_output' ] );
 
 		$this->assertEquals( [], $sitemap_provider->get_excluded_posts( 'post' ) );
 
-		remove_filter( 'wpseo_exclude_from_sitemap_by_post_ids', [ $this, 'filter_with_invalid_output' ] );
+		\remove_filter( 'wpseo_exclude_from_sitemap_by_post_ids', [ $this, 'filter_with_invalid_output' ] );
 	}
 
 	/**
@@ -265,7 +264,7 @@ public function filter_with_invalid_output( $excluded_post_ids ) {
 	 * @covers ::get_url
 	 */
 	public function test_get_url() {
-		$current_home     = get_option( 'home' );
+		$current_home     = \get_option( 'home' );
 		$sitemap_provider = new Post_Type_Sitemap_Provider_Double();
 
 		$post_object = $this->factory()->post->create_and_get();
@@ -274,14 +273,14 @@ public function test_get_url() {
 		$this->assertStringContainsString( $current_home, $post_url['loc'] );
 
 		// Change home URL.
-		update_option( 'home', 'http://example.com' );
-		wp_cache_delete( 'alloptions', 'options' );
+		\update_option( 'home', 'http://example.com' );
+		\wp_cache_delete( 'alloptions', 'options' );
 
 		$this->assertFalse( $sitemap_provider->get_url( $post_object ) );
 
 		// Revert original home URL.
-		update_option( 'home', $current_home );
-		wp_cache_delete( 'alloptions', 'options' );
+		\update_option( 'home', $current_home );
+		\wp_cache_delete( 'alloptions', 'options' );
 	}
 
 	/**
diff --git a/tests/WP/Sitemaps/test-class-wpseo-sitemap-provider-overlap.php b/tests/WP/Sitemaps/Provider_Overlap_Test.php
similarity index 81%
rename from tests/WP/Sitemaps/test-class-wpseo-sitemap-provider-overlap.php
rename to tests/WP/Sitemaps/Provider_Overlap_Test.php
index 10a2ac751fc..b307763e7db 100644
--- a/tests/WP/Sitemaps/test-class-wpseo-sitemap-provider-overlap.php
+++ b/tests/WP/Sitemaps/Provider_Overlap_Test.php
@@ -1,21 +1,19 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Sitemaps
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Sitemaps;
+
+use WPSEO_Options;
 use Yoast\WP\SEO\Tests\WP\Doubles\Inc\Sitemaps_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
- * Class WPSEO_Sitemap_Provider_Overlap_Test.
+ * Class Provider_Overlap_Test.
  *
  * @group sitemaps
  *
  * @covers WPSEO_Sitemaps
  */
-class WPSEO_Sitemap_Provider_Overlap_Test extends TestCase {
+class Provider_Overlap_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
@@ -46,14 +44,14 @@ public function set_up() {
 		self::$class_instance->reset();
 
 		// Create private taxonomy "author", overlapping the "author" sitemap.
-		register_taxonomy( 'author', [ 'post' ], [ 'public' => false ] );
+		\register_taxonomy( 'author', [ 'post' ], [ 'public' => false ] );
 	}
 
 	/**
 	 * Clean up the taxonomy.
 	 */
 	public function tear_down() {
-		unregister_taxonomy( 'author' );
+		\unregister_taxonomy( 'author' );
 		parent::tear_down();
 	}
 
@@ -66,12 +64,12 @@ public function test_private_taxonomy_author_overlap() {
 		$this->factory->post->create_many( 1, [ 'post_author' => $user_id ] );
 
 		// Fetch the global sitemap.
-		set_query_var( 'sitemap', '1' );
+		\set_query_var( 'sitemap', '1' );
 
 		// Load the sitemap.
 		self::$class_instance->redirect( $GLOBALS['wp_the_query'] );
 
-		$url = home_url( 'author-sitemap.xml' );
+		$url = \home_url( 'author-sitemap.xml' );
 
 		// Expect the author-sitemap to be present in the index.
 		$this->expectOutputContains(
@@ -88,14 +86,14 @@ public function test_private_taxonomy_author_overlap_author_in_sitemap() {
 		$this->factory->post->create_many( 1, [ 'post_author' => $user_id ] );
 
 		// Fetch the global sitemap.
-		set_query_var( 'sitemap', 'author' );
+		\set_query_var( 'sitemap', 'author' );
 
 		// Load the sitemap.
 		self::$class_instance->redirect( $GLOBALS['wp_the_query'] );
 
 		// Expect the author-sitemap to be present in the index.
 		$this->expectOutputContains(
-			'<loc>' . get_author_posts_url( $user_id ) . '</loc>'
+			'<loc>' . \get_author_posts_url( $user_id ) . '</loc>'
 		);
 	}
 }
diff --git a/tests/WP/Sitemaps/test-class-wpseo-sitemaps-renderer.php b/tests/WP/Sitemaps/Renderer_Test.php
similarity index 93%
rename from tests/WP/Sitemaps/test-class-wpseo-sitemaps-renderer.php
rename to tests/WP/Sitemaps/Renderer_Test.php
index 3a234d741fb..2c0254d40dc 100644
--- a/tests/WP/Sitemaps/test-class-wpseo-sitemaps-renderer.php
+++ b/tests/WP/Sitemaps/Renderer_Test.php
@@ -1,19 +1,17 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Sitemaps
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Sitemaps;
+
+use WPSEO_Sitemaps_Renderer;
 use Yoast\WP\SEO\Tests\WP\Doubles\Inc\Sitemaps_Renderer_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
- * Class WPSEO_Sitemaps_Renderer_Test.
+ * Class Renderer_Test.
  *
  * @group sitemaps
  */
-class WPSEO_Sitemaps_Renderer_Test extends TestCase {
+class Renderer_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
@@ -39,7 +37,7 @@ public function set_up() {
 	public function test_get_index() {
 
 		$loc     = 'http://example.com/';
-		$lastmod = date( 'c' );
+		$lastmod = \date( 'c' );
 		$links   = [
 			[
 				'loc'     => $loc,
@@ -60,7 +58,7 @@ public function test_get_index() {
 	public function test_get_sitemap() {
 
 		$loc     = 'http://example.com/?s=keyword&p=2';
-		$mod     = date( 'c' );
+		$mod     = \date( 'c' );
 		$image_a = 'http://example.com/image.jpg';
 		$image_b = 'example.com/my category/my=page*without"enco@ding/';
 		$image_c = '//example.com/my category?s=keyword&p=2';
@@ -88,7 +86,7 @@ public function test_get_sitemap() {
 		$expected_c = 'http://example.com/my%20category?s=keyword&amp;p=2';
 
 		$index = self::$class_instance->get_sitemap( $links, 'post', 0 );
-		$this->assertStringContainsString( '<loc>' . str_replace( '&', '&amp;', $loc ) . '</loc>', $index );
+		$this->assertStringContainsString( '<loc>' . \str_replace( '&', '&amp;', $loc ) . '</loc>', $index );
 		$this->assertStringContainsString( "<lastmod>{$mod}</lastmod>", $index );
 		$this->assertStringContainsString( "<image:loc>{$image_a}</image:loc>", $index );
 		$this->assertStringContainsString( "<image:loc>{$expected_b}</image:loc>", $index );
@@ -195,8 +193,8 @@ public function change_plugin_url() {
 	public function test_is_home_url_returned_correctly() {
 		$class_instance = new Sitemaps_Renderer_Double();
 
-		add_filter( 'plugins_url', [ $this, 'change_plugin_url' ] );
+		\add_filter( 'plugins_url', [ $this, 'change_plugin_url' ] );
 		$this->assertEquals( 'http://example.org/main-sitemap.xsl', $class_instance->get_xsl_url() );
-		remove_filter( 'plugins_url', [ $this, 'change_plugin_url' ] );
+		\remove_filter( 'plugins_url', [ $this, 'change_plugin_url' ] );
 	}
 }
diff --git a/tests/WP/Sitemaps/test-class-wpseo-sitemaps-router.php b/tests/WP/Sitemaps/Router_Test.php
similarity index 88%
rename from tests/WP/Sitemaps/test-class-wpseo-sitemaps-router.php
rename to tests/WP/Sitemaps/Router_Test.php
index 85074a71cd3..15b5ac72a85 100644
--- a/tests/WP/Sitemaps/test-class-wpseo-sitemaps-router.php
+++ b/tests/WP/Sitemaps/Router_Test.php
@@ -1,18 +1,17 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Sitemaps
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Sitemaps;
+
+use WP_Query;
+use WPSEO_Sitemaps_Router;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
- * Class WPSEO_Sitemaps_Router_Test.
+ * Class Router_Test.
  *
  * @group sitemaps
  */
-class WPSEO_Sitemaps_Router_Test extends TestCase {
+class Router_Test extends TestCase {
 
 	/**
 	 * Temporary home URL storage.
@@ -46,14 +45,14 @@ public function test_redirect_canonical() {
 		unset( $wp_query->query_vars['sitemap'] );
 		unset( $wp_query->query_vars['xls'] );
 
-		$url = site_url();
+		$url = \site_url();
 
 		$this->assertNotEmpty( self::$class_instance->redirect_canonical( $url ) );
 
-		set_query_var( 'sitemap', 'sitemap_value' );
+		\set_query_var( 'sitemap', 'sitemap_value' );
 		$this->assertFalse( self::$class_instance->redirect_canonical( $url ) );
 
-		set_query_var( '$yoast_sitemap_xsl', 'xsl_value' );
+		\set_query_var( '$yoast_sitemap_xsl', 'xsl_value' );
 		$this->assertFalse( self::$class_instance->redirect_canonical( $url ) );
 	}
 
@@ -67,7 +66,7 @@ public function test_redirect_canonical() {
 	 * @param string $expected The expected test result.
 	 */
 	public function test_get_base_url( $home_url, $expected ) {
-		update_option( 'home', $home_url );
+		\update_option( 'home', $home_url );
 		$this->assertSame( $expected, WPSEO_Sitemaps_Router::get_base_url( 'sitemap.xml' ) );
 	}
 
@@ -108,13 +107,13 @@ public function test_needs_sitemap_index_redirect( $server_vars, $home_url, $wp_
 		$server_orig   = $_SERVER;
 		$wp_query_orig = $GLOBALS['wp_query'];
 
-		$_SERVER             = array_merge( $_SERVER, $server_vars );
+		$_SERVER             = \array_merge( $_SERVER, $server_vars );
 		$this->home_url      = $home_url;
 		$GLOBALS['wp_query'] = $wp_query;
 
-		add_filter( 'home_url', [ $this, 'filter_home_url' ], 100, 2 );
+		\add_filter( 'home_url', [ $this, 'filter_home_url' ], 100, 2 );
 		$result = self::$class_instance->needs_sitemap_index_redirect();
-		remove_filter( 'home_url', [ $this, 'filter_home_url' ], 100 );
+		\remove_filter( 'home_url', [ $this, 'filter_home_url' ], 100 );
 
 		$GLOBALS['wp_query'] = $wp_query_orig;
 		$this->home_url      = '';
@@ -134,7 +133,7 @@ public function test_needs_sitemap_index_redirect( $server_vars, $home_url, $wp_
 	public function filter_home_url( $home_url, $path ) {
 		if ( ! empty( $this->home_url ) ) {
 			if ( ! empty( $path ) ) {
-				return $this->home_url . '/' . ltrim( $path, '/' );
+				return $this->home_url . '/' . \ltrim( $path, '/' );
 			}
 			return $this->home_url;
 		}
@@ -206,7 +205,7 @@ public function data_needs_sitemap_index_redirect() {
 					$testdata[] = [ $server_vars, $home_url, $wp_query, $expected ];
 
 					$expected   = $home_url === 'https://' . $domain && $path === '/sitemap.xml' && $wp_query->is_404;
-					$testdata[] = [ array_merge( $server_vars, [ 'HTTPS' => 'on' ] ), $home_url, $wp_query, $expected ];
+					$testdata[] = [ \array_merge( $server_vars, [ 'HTTPS' => 'on' ] ), $home_url, $wp_query, $expected ];
 				}
 			}
 		}
diff --git a/tests/WP/Sitemaps/test-class-wpseo-sitemaps.php b/tests/WP/Sitemaps/Sitemaps_Test.php
similarity index 90%
rename from tests/WP/Sitemaps/test-class-wpseo-sitemaps.php
rename to tests/WP/Sitemaps/Sitemaps_Test.php
index 9d0f8d80316..18e7b2456ce 100644
--- a/tests/WP/Sitemaps/test-class-wpseo-sitemaps.php
+++ b/tests/WP/Sitemaps/Sitemaps_Test.php
@@ -1,19 +1,17 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Sitemaps
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Sitemaps;
+
+use WPSEO_Sitemaps;
 use Yoast\WP\SEO\Tests\WP\Doubles\Inc\Sitemaps_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
- * Class WPSEO_Sitemaps_Test.
+ * Class Sitemaps_Test.
  *
  * @group sitemaps
  */
-class WPSEO_Sitemaps_Test extends TestCase {
+class Sitemaps_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
@@ -43,7 +41,7 @@ public function set_up() {
 	public function test_post_sitemap( $expected_output ) {
 		self::$class_instance->reset();
 
-		set_query_var( 'sitemap', 'post' );
+		\set_query_var( 'sitemap', 'post' );
 
 		self::$class_instance->redirect( $GLOBALS['wp_the_query'] );
 
@@ -75,7 +73,7 @@ public function test_main_sitemap( $expected_output ) {
 
 		self::$class_instance->reset();
 
-		set_query_var( 'sitemap', '1' );
+		\set_query_var( 'sitemap', '1' );
 
 		$this->factory->post->create();
 
@@ -107,16 +105,16 @@ public function test_index_links_filter() {
 
 		self::$class_instance->reset();
 
-		set_query_var( 'sitemap', '1' );
+		\set_query_var( 'sitemap', '1' );
 
 		$this->factory->post->create();
 
-		add_filter(
+		\add_filter(
 			'wpseo_sitemap_index_links',
 			static function( $links ) {
 				$links[] = [
 					'loc'     => 'test-sitemap.xml',
-					'lastmod' => date( '1' ),
+					'lastmod' => \date( '1' ),
 				];
 				return $links;
 			}
@@ -141,7 +139,7 @@ public function test_last_modified_post_type() {
 			'public'      => true,
 			'has_archive' => true,
 		];
-		register_post_type( 'yoast', $post_type_args );
+		\register_post_type( 'yoast', $post_type_args );
 
 		$post_args = [
 			'post_status' => 'publish',
diff --git a/tests/WP/Sitemaps/test-class-wpseo-taxonomy-sitemap-provider.php b/tests/WP/Sitemaps/Taxonomy_Sitemap_Provider_Test.php
similarity index 85%
rename from tests/WP/Sitemaps/test-class-wpseo-taxonomy-sitemap-provider.php
rename to tests/WP/Sitemaps/Taxonomy_Sitemap_Provider_Test.php
index 44714b5ea1d..ae6e1a5bf65 100644
--- a/tests/WP/Sitemaps/test-class-wpseo-taxonomy-sitemap-provider.php
+++ b/tests/WP/Sitemaps/Taxonomy_Sitemap_Provider_Test.php
@@ -1,20 +1,18 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Sitemaps
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Sitemaps;
+
+use WPSEO_Taxonomy_Sitemap_Provider;
 use Yoast\WP\SEO\Tests\WP\Doubles\Inc\Sitemaps_Double;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
- * Class WPSEO_Taxonomy_Sitemap_Provider_Test.
+ * Class Taxonomy_Sitemap_Provider_Test.
  *
  * @group sitemaps
  * @coversDefaultClass WPSEO_Taxonomy_Sitemap_Provider
  */
-class WPSEO_Taxonomy_Sitemap_Provider_Test extends TestCase {
+class Taxonomy_Sitemap_Provider_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
@@ -44,7 +42,7 @@ public function test_get_index_links() {
 
 		$category_id = $this->factory->category->create();
 		$post_id     = $this->factory->post->create();
-		wp_set_post_categories( $post_id, $category_id );
+		\wp_set_post_categories( $post_id, $category_id );
 
 		$index_links = self::$class_instance->get_index_links( 1 );
 		$this->assertNotEmpty( $index_links );
@@ -52,7 +50,7 @@ public function test_get_index_links() {
 
 		$category2_id = $this->factory->category->create();
 		$post2_id     = $this->factory->post->create();
-		wp_set_post_categories( $post2_id, $category2_id );
+		\wp_set_post_categories( $post2_id, $category2_id );
 		$index_links = self::$class_instance->get_index_links( 1 );
 		$this->assertContains( 'http://example.org/category-sitemap.xml', $index_links[0] );
 		$this->assertContains( 'http://example.org/category-sitemap2.xml', $index_links[1] );
@@ -67,9 +65,9 @@ public function test_get_sitemap_links() {
 
 		$category_id = $this->factory->category->create();
 		$post_id     = $this->factory->post->create();
-		wp_set_post_categories( $post_id, $category_id );
+		\wp_set_post_categories( $post_id, $category_id );
 		$sitemap_links = self::$class_instance->get_sitemap_links( 'category', 1, 1 );
-		$this->assertContains( get_category_link( $category_id ), $sitemap_links[0] );
+		$this->assertContains( \get_category_link( $category_id ), $sitemap_links[0] );
 	}
 
 	/**
@@ -79,10 +77,10 @@ public function test_get_sitemap_links() {
 	 */
 	public function test_get_index_links_empty_sitemap() {
 		// Fetch the global sitemap.
-		set_query_var( 'sitemap', 'category' );
+		\set_query_var( 'sitemap', 'category' );
 
 		// Set the page to the second one, which should not contain an entry, and should not exist.
-		set_query_var( 'sitemap_n', '2' );
+		\set_query_var( 'sitemap_n', '2' );
 
 		// Load the sitemap.
 		$sitemaps = new Sitemaps_Double();
diff --git a/tests/WP/Statistics/test-class-statistics-service.php b/tests/WP/Statistics/Statistics_Service_Test.php
similarity index 84%
rename from tests/WP/Statistics/test-class-statistics-service.php
rename to tests/WP/Statistics/Statistics_Service_Test.php
index e340ddfa6b5..c2d848a2c5b 100644
--- a/tests/WP/Statistics/test-class-statistics-service.php
+++ b/tests/WP/Statistics/Statistics_Service_Test.php
@@ -1,10 +1,8 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Statistics
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Statistics;
+
+use WPSEO_Statistics_Service;
 use Yoast\WP\SEO\Tests\WP\Doubles\Inc\Statistics_Mock;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
@@ -13,13 +11,13 @@
  *
  * @coversDefaultClass WPSEO_Statistics_Service
  */
-class WPSEO_Statistics_Service_Test extends TestCase {
+class Statistics_Service_Test extends TestCase {
 
 	/**
 	 * Reset after each test.
 	 */
 	public function tear_down() {
-		delete_transient( WPSEO_Statistics_Service::CACHE_TRANSIENT_KEY );
+		\delete_transient( WPSEO_Statistics_Service::CACHE_TRANSIENT_KEY );
 
 		parent::tear_down();
 	}
@@ -65,7 +63,7 @@ public function test_seo_score_links() {
 		$response_data  = $rest_response->get_data();
 
 		$this->assertEquals(
-			esc_url( admin_url( 'edit.php?post_status=publish&post_type=post&seo_filter=ok&author=0' ) ),
+			\esc_url( \admin_url( 'edit.php?post_status=publish&post_type=post&seo_filter=ok&author=0' ) ),
 			$response_data['seo_scores'][0]['link']
 		);
 	}
@@ -76,7 +74,7 @@ public function test_seo_score_links() {
 	 * @covers ::get_statistics
 	 */
 	public function test_admin_seo_score_links() {
-		$user = wp_get_current_user();
+		$user = \wp_get_current_user();
 		$user->add_cap( 'edit_others_posts' );
 
 		$statistics = new Statistics_Mock(
@@ -92,7 +90,7 @@ public function test_admin_seo_score_links() {
 		$response_data  = $rest_response->get_data();
 
 		$this->assertEquals(
-			esc_url( admin_url( 'edit.php?post_status=publish&post_type=post&seo_filter=ok' ) ),
+			\esc_url( \admin_url( 'edit.php?post_status=publish&post_type=post&seo_filter=ok' ) ),
 			$response_data['seo_scores'][0]['link']
 		);
 
diff --git a/tests/WP/Taxonomy/test-class-taxonomy-presenter.php b/tests/WP/Taxonomy/Taxonomy_Fields_Presenter_Test.php
similarity index 94%
rename from tests/WP/Taxonomy/test-class-taxonomy-presenter.php
rename to tests/WP/Taxonomy/Taxonomy_Fields_Presenter_Test.php
index a5259ca3904..2e89bdb94c6 100644
--- a/tests/WP/Taxonomy/test-class-taxonomy-presenter.php
+++ b/tests/WP/Taxonomy/Taxonomy_Fields_Presenter_Test.php
@@ -1,16 +1,14 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Taxonomy
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Taxonomy;
+
+use WPSEO_Taxonomy_Fields_Presenter;
 use Yoast\WP\SEO\Tests\WP\TestCase;
 
 /**
  * Unit Test Class.
  */
-class WPSEO_Taxonomy_Presenter_Test extends TestCase {
+class Taxonomy_Fields_Presenter_Test extends TestCase {
 
 	/**
 	 * Holds the instance of the class being tested.
@@ -54,7 +52,7 @@ public function test_display_fields() {
 		);
 
 		$expected = '<label for="wpseo_fieldname">test field</label><input name="wpseo_fieldname" id="wpseo_fieldname"  type="text" value="" size="40" aria-describedby="wpseo_fieldname-desc"/><p id="wpseo_fieldname-desc" class="yoast-metabox__description">this is a test field</p>';
-		$expected = sprintf( $expected, plugins_url( 'images/question-mark.png', WPSEO_FILE ) );
+		$expected = \sprintf( $expected, \plugins_url( 'images/question-mark.png', \WPSEO_FILE ) );
 
 		$this->assertEquals( $expected, $output );
 	}
@@ -77,7 +75,7 @@ public function test_display_fields_no_label() {
 		);
 
 		$expected = '<input name="wpseo_fieldname" id="wpseo_fieldname"  type="text" value="" size="40" aria-describedby="wpseo_fieldname-desc"/><p id="wpseo_fieldname-desc" class="yoast-metabox__description">this is a test field</p>';
-		$expected = sprintf( $expected, plugins_url( 'images/question-mark.png', WPSEO_FILE ) );
+		$expected = \sprintf( $expected, \plugins_url( 'images/question-mark.png', \WPSEO_FILE ) );
 
 		$this->assertEquals( $expected, $output );
 	}
diff --git a/tests/WP/Taxonomy/test-class-taxonomy.php b/tests/WP/Taxonomy/Taxonomy_Test.php
similarity index 93%
rename from tests/WP/Taxonomy/test-class-taxonomy.php
rename to tests/WP/Taxonomy/Taxonomy_Test.php
index 2b84c59e81a..90180b05bbb 100644
--- a/tests/WP/Taxonomy/test-class-taxonomy.php
+++ b/tests/WP/Taxonomy/Taxonomy_Test.php
@@ -1,10 +1,8 @@
 <?php
-/**
- * WPSEO plugin test file.
- *
- * @package WPSEO\Tests\Taxonomy
- */
 
+namespace Yoast\WP\SEO\Tests\WP\Taxonomy;
+
+use WPSEO_Taxonomy;
 use Yoast\WPTestUtils\WPIntegration\TestCase;
 
 /**
@@ -12,7 +10,7 @@
  *
  * @coversDefaultClass WPSEO_Taxonomy
  */
-class WPSEO_Taxonomy_Test extends TestCase {
+class Taxonomy_Test extends TestCase {
 
 	/**
 	 * Make sure certain pages are marked as term edit.