SONARKT-302 - Implement rule S6526: abstract class should be interface (

#384)

its/ruling/src/test/resources/expected/kotlin/android-architecture-components/kotlin-S6526.json

@@ -0,0 +1,11 @@
+{
+"kotlin-android-architecture-components-project:sources/kotlin/android-architecture-components/GithubBrowserSample/app/src/main/java/com/android/example/github/di/FragmentBuildersModule.kt": [
+28
+],
+"kotlin-android-architecture-components-project:sources/kotlin/android-architecture-components/GithubBrowserSample/app/src/main/java/com/android/example/github/di/MainActivityModule.kt": [
+26
+],
+"kotlin-android-architecture-components-project:sources/kotlin/android-architecture-components/GithubBrowserSample/app/src/main/java/com/android/example/github/di/ViewModelModule.kt": [
+33
+]
+}

its/ruling/src/test/resources/expected/kotlin/corda/kotlin-S6526.json

@@ -0,0 +1,45 @@
+{
+"kotlin-corda-project:sources/kotlin/corda/client/jackson/src/main/kotlin/net/corda/client/jackson/JacksonSupport.kt": [
+487,
+501
+],
+"kotlin-corda-project:sources/kotlin/corda/core/src/main/kotlin/net/corda/core/node/services/vault/QueryCriteriaUtils.kt": [
+146
+],
+"kotlin-corda-project:sources/kotlin/corda/node/src/integration-test/kotlin/net/corda/node/amqp/AMQPBridgeTest.kt": [
+46
+],
+"kotlin-corda-project:sources/kotlin/corda/node/src/integration-test/kotlin/net/corda/node/amqp/CertificateRevocationListNodeTests.kt": [
+75
+],
+"kotlin-corda-project:sources/kotlin/corda/node/src/integration-test/kotlin/net/corda/node/amqp/ProtonWrapperTests.kt": [
+50
+],
+"kotlin-corda-project:sources/kotlin/corda/node/src/test/kotlin/net/corda/node/internal/NodeTest.kt": [
+33
+],
+"kotlin-corda-project:sources/kotlin/corda/node/src/test/kotlin/net/corda/node/services/messaging/ArtemisMessagingTest.kt": [
+67
+],
+"kotlin-corda-project:sources/kotlin/corda/node/src/test/kotlin/net/corda/node/utilities/registration/NetworkRegistrationHelperTest.kt": [
+54
+],
+"kotlin-corda-project:sources/kotlin/corda/serialization/src/main/kotlin/net/corda/serialization/internal/amqp/EvolutionSerializer.kt": [
+250
+],
+"kotlin-corda-project:sources/kotlin/corda/serialization/src/main/kotlin/net/corda/serialization/internal/amqp/PropertySerializers.kt": [
+12
+],
+"kotlin-corda-project:sources/kotlin/corda/serialization/src/test/kotlin/net/corda/serialization/internal/CordaClassResolverTests.kt": [
+68
+],
+"kotlin-corda-project:sources/kotlin/corda/serialization/src/test/kotlin/net/corda/serialization/internal/amqp/SerializationOutputTests.kt": [
+212
+],
+"kotlin-corda-project:sources/kotlin/corda/testing/node-driver/src/main/kotlin/net/corda/testing/node/internal/InternalMockNetwork.kt": [
+461
+],
+"kotlin-corda-project:sources/kotlin/corda/testing/test-utils/src/test/kotlin/net/corda/testing/internal/RigorousMockTest.kt": [
+18
+]
+}

its/ruling/src/test/resources/expected/kotlin/kotlin/kotlin-S6526.json

@@ -0,0 +1,115 @@
+{
+"kotlin-kotlin-project:sources/kotlin/kotlin/compiler/container/tests/org/jetbrains/kotlin/container/tests/ComponentContainerTest.kt": [
+316
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/compiler/frontend/src/org/jetbrains/kotlin/analyzer/AnalyzerFacade.kt": [
+310
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/LocalDeclarationsLowering.kt": [
+86
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/tower/TowerResolver.kt": [
+291
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/compiler/tests/org/jetbrains/kotlin/codegen/AbstractCustomScriptCodegenTest.kt": [
+139,
+150
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/compiler/tests/org/jetbrains/kotlin/daemon/CompilerDaemonTest.kt": [
+927
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/compiler/tests/org/jetbrains/kotlin/scripts/ScriptTemplateTest.kt": [
+563,
+587,
+590,
+593
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/core/builtins/native/kotlin/Number.kt": [
+22
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/core/descriptors.runtime/src/kotlin/reflect/jvm/internal/structure/ReflectJavaElement.kt": [
+21
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/idea/formatter/src/org/jetbrains/kotlin/idea/formatter/CommonAlignmentStrategy.kt": [
+22
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/idea/idea-analysis/src/org/jetbrains/kotlin/idea/configuration/BuildSystemType.kt": [
+12
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/idea/idea-analysis/src/org/jetbrains/kotlin/idea/decompiler/stubBuilder/flags/flags.kt": [
+24
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/idea/idea-jvm/src/org/jetbrains/kotlin/idea/debugger/stepping/KotlinStepActionFactory.kt": [
+36
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/js/js.translator/src/org/jetbrains/kotlin/js/translate/intrinsic/functions/basic/FunctionIntrinsic.kt": [
+26
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/libraries/examples/scripting/jvm-maven-deps/script/src/org/jetbrains/kotlin/script/examples/jvm/resolve/maven/scriptDef.kt": [
+28
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/libraries/examples/scripting/jvm-simple-script/script/src/org/jetbrains/kotlin/script/examples/jvm/simple/scriptDef.kt": [
+16
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/libraries/stdlib/js/src/org.w3c/org.khronos.webgl.kt": [
+69,
+75,
+81,
+87,
+93,
+99,
+105,
+111
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/libraries/stdlib/js/src/org.w3c/org.w3c.dom.kt": [
+280,
+335,
+341,
+356,
+543,
+581,
+719
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/libraries/stdlib/js/src/org.w3c/org.w3c.dom.svg.kt": [
+368,
+371,
+377,
+383,
+389,
+395,
+401,
+436,
+540,
+587,
+615,
+621,
+661,
+667,
+735,
+779,
+782,
+785,
+814,
+817
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/libraries/stdlib/js/src/org.w3c/org.w3c.xhr.kt": [
+39
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/libraries/tools/binary-compatibility-validator/src/test/kotlin/cases/companions/companions.kt": [
+13,
+47,
+80
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/libraries/tools/binary-compatibility-validator/src/test/kotlin/cases/nestedClasses/publicAbstractClass.kt": [
+3
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/libraries/tools/kotlin-maven-plugin-test/src/it/test-dagger-maven-example/src/main/kotlin/PumpModule.kt": [
+7
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/libraries/tools/kotlin-maven-plugin-test/src/it/test-kapt-allopen/src/main/kotlin/PumpModule.kt": [
+7
+],
+"kotlin-kotlin-project:sources/kotlin/kotlin/plugins/sam-with-receiver/sam-with-receiver-cli/test/org/jetbrains/kotlin/samWithReceiver/AbstractSamWithReceiverScriptTest.kt": [
+41
+]
+}

its/ruling/src/test/resources/expected/kotlin/ktor/kotlin-S6526.json

@@ -0,0 +1,13 @@
+{
+"kotlin-ktor-project:sources/kotlin/ktor/ktor-io/common/src/io/ktor/utils/io/charsets/Encoding.kt": [
+20,
+90
+],
+"kotlin-ktor-project:sources/kotlin/ktor/ktor-utils/common/src/io/ktor/util/internal/LockFreeLinkedList.kt": [
+58,
+114
+],
+"kotlin-ktor-project:sources/kotlin/ktor/ktor-utils/common/src/io/ktor/util/network/NetworkAddress.kt": [
+14
+]
+}

kotlin-checks-test-sources/src/main/kotlin/checks/AbstractClassShouldBeInterfaceCheckSample.kt

@@ -0,0 +1,96 @@
+package checks
+
+class AbstractClassShouldBeInterfaceCheckSample {
+
+    abstract class ShapeA { // Noncompliant {{Replace this abstract class with an interface, or add function implementations or state properties to the class.}}
+//                 ^^^^^^
+        abstract fun getPath(): Int
+        abstract fun getBoundingBox(): Pair<Int,Int>
+    }
+
+    interface ShapeB { // Compliant, we are using an interface here
+        fun getPath(): Int
+        fun getBoundingBox(): Pair<Int,Int>
+    }
+
+
+    abstract class ShapeC { // Compliant, abstract class has function implementations
+        abstract fun getPath(): Int
+        fun getBoundingBox(): Pair<Int,Int> {
+            return Pair(0,0)
+        }
+    }
+
+    abstract class Foo { // Noncompliant
+        abstract var bar: String
+        abstract val baz: String
+    }
+
+    abstract class Bar { // compliant
+        var bar: String = ""
+        abstract val baz: String
+    }
+
+    abstract class A { // Noncompliant
+        abstract class Inner { // Noncompliant
+            abstract fun foo()
+        }
+    }
+
+    abstract class B { // Compliant
+        abstract class Inner {
+            fun foo() {}
+        }
+    }
+
+    abstract class C { // Noncompliant
+        object Inner {
+
+        }
+    }
+
+
+    abstract class D { // Compliant
+        companion object Inner {
+            fun foo() {}
+        }
+    }
+
+    interface E { // Compliant
+        object Inner {
+
+        }
+    }
+
+    abstract class F { // Compliant, at least one property in the initializer
+        init {
+            val x = 0
+        }
+    }
+
+    abstract class G { // Compliant
+        constructor() {
+            val x = 0
+        }
+    }
+
+    abstract class I { // Noncompliant
+        init {
+        }
+    }
+
+    abstract class J { // Compliant
+        constructor() {
+        }
+    }
+
+    abstract class K {} // Noncompliant
+    abstract class L : K() {} // compliant, extend an abstract as he may have no other choice
+
+    interface M {} // compliant
+    abstract class N : M {} // Noncompliant
+    abstract class O : K(), M {} // compliant
+
+    abstract interface ZZZ { // Compliant
+    }
+}

sonar-kotlin-checks/src/main/java/org/sonarsource/kotlin/checks/AbstractClassShouldBeInterfaceCheck.kt

@@ -0,0 +1,57 @@
+/*
+ * SonarSource Kotlin
+ * Copyright (C) 2018-2023 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonarsource.kotlin.checks
+
+import org.jetbrains.kotlin.lexer.KtTokens
+import org.jetbrains.kotlin.psi.KtClass
+import org.jetbrains.kotlin.psi.KtDeclaration
+import org.jetbrains.kotlin.psi.KtFunction
+import org.jetbrains.kotlin.psi.KtProperty
+import org.jetbrains.kotlin.psi.KtSuperTypeCallEntry
+import org.jetbrains.kotlin.psi.psiUtil.collectDescendantsOfType
+import org.sonar.check.Rule
+import org.sonarsource.kotlin.api.checks.AbstractCheck
+import org.sonarsource.kotlin.api.frontend.KotlinFileContext
+
+@Rule(key = "S6526")
+class AbstractClassShouldBeInterfaceCheck : AbstractCheck() {
+
+    override fun visitClass(klass: KtClass, context: KotlinFileContext) {
+
+        if (!klass.isAbstract() || klass.isInterface() || klass.extendsClass()) return
+
+        val allMethods = klass.collectDescendantsOfType<KtFunction>()
+        val allProperties: List<KtProperty> by lazy { klass.collectDescendantsOfType<KtProperty>() }
+
+        if (allMethods.all { it.isAbstract() } && allProperties.all { it.isAbstract() }) {
+            context.reportIssue(
+                klass.nameIdentifier!!,
+                "Replace this abstract class with an interface, or add function implementations or state properties to the class."
+            )
+        }
+    }
+
+    private fun KtClass.extendsClass(): Boolean {
+        return superTypeListEntries.any { it is KtSuperTypeCallEntry }
+    }
+
+    private fun KtDeclaration.isAbstract() = hasModifier(KtTokens.ABSTRACT_KEYWORD)
+
+}

sonar-kotlin-checks/src/test/java/org/sonarsource/kotlin/checks/AbstractClassShouldBeInterfaceCheckTest.kt

@@ -0,0 +1,22 @@
+/*
+ * SonarSource Kotlin
+ * Copyright (C) 2018-2023 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonarsource.kotlin.checks
+
+internal class AbstractClassShouldBeInterfaceCheckTest : CheckTest(AbstractClassShouldBeInterfaceCheck())

sonar-kotlin-plugin/src/main/java/org/sonarsource/kotlin/plugin/KotlinCheckList.kt

@@ -19,6 +19,7 @@
  */
 package org.sonarsource.kotlin.plugin
 
+import org.sonarsource.kotlin.checks.AbstractClassShouldBeInterfaceCheck
 import org.sonarsource.kotlin.checks.AllBranchesIdenticalCheck
 import org.sonarsource.kotlin.checks.AnchorPrecedenceCheck
 import org.sonarsource.kotlin.checks.AndroidBroadcastingCheck
@@ -149,6 +150,7 @@ import org.sonarsource.kotlin.checks.WebViewsFileAccessCheck
 import org.sonarsource.kotlin.checks.WrongAssignmentOperatorCheck
 
 val KOTLIN_CHECKS = listOf(
+    AbstractClassShouldBeInterfaceCheck::class.java,
     AllBranchesIdenticalCheck::class.java,
     AnchorPrecedenceCheck::class.java,
     AndroidBroadcastingCheck::class.java,