Added model tests, user.rb so it has many articles.

app/models/user.rb

@@ -1,6 +1,6 @@
 class User < ApplicationRecord
   has_secure_password
-  has_many :article, foreign_key: "author_id"
+  has_many :articles, foreign_key: "user_id"
 
   validates :name, presence: true, uniqueness: true
   validates :email, presence: true, uniqueness: true

test/controllers/users_controller_test.rb

@@ -3,7 +3,7 @@
 class UsersControllerTest < ActionDispatch::IntegrationTest
   include FactoryBot::Syntax::Methods
 
-  def setup
+  setup do
     @user = create(:user)
     @valid_user_params = {user: attributes_for(:user)}
     @invalid_user_params = {user: {name: "", email: "invalid", password: "pass", password_confirmation: "word"}}

test/factories/articles.rb

@@ -2,6 +2,6 @@
   factory :article do
     title { "Ruby on Rails" }
     link { "https://rubyonrails.org/" }
-    association :user
+    association :user, factory: :user
   end
 end

test/models/article_test.rb

@@ -1,8 +1,10 @@
 require "test_helper"
 
 class ArticleTest < ActiveSupport::TestCase
+  include FactoryBot::Syntax::Methods
+
   setup do
-    @article = FactoryBot.build(:article)
+    @article = build(:article)
   end
 
   test "should be valid with valid attributes" do
@@ -11,11 +13,16 @@ class ArticleTest < ActiveSupport::TestCase
 
   test "should not be valid without a title" do
     @article.title = nil
-    assert_not @article.valid?
+    assert_not @article.valid?, "Article is valid without a title"
   end
 
   test "should not be valid without a link" do
     @article.link = nil
-    assert_not @article.valid?
+    assert_not @article.valid?, "Article is valid without a link"
+  end
+
+  test "should not be valid without a user" do
+    @article.user = nil
+    assert_not @article.valid?, "Article is valid without a user"
   end
 end

test/models/user_test.rb

@@ -0,0 +1,44 @@
+require "test_helper"
+
+class UserTest < ActiveSupport::TestCase
+  include FactoryBot::Syntax::Methods
+  setup do
+    @user = create(:user)
+  end
+
+  test "should be valid" do
+    assert @user.valid?
+  end
+
+  test "name should be present" do
+    @user.name = ""
+    assert_not @user.valid?
+  end
+
+  test "email should be present" do
+    @user.email = ""
+    assert_not @user.valid?
+  end
+
+  test "name should be unique" do
+    duplicate_user = @user.dup
+    @user.save
+    assert_not duplicate_user.valid?
+  end
+
+  test "email should be unique" do
+    duplicate_user = @user.dup
+    duplicate_user.email = @user.email.upcase
+    @user.save
+    assert_not duplicate_user.valid?
+  end
+
+  test "password should be present (nonblank)" do
+    @user.password = @user.password_confirmation = ""
+    assert_not @user.valid?
+  end
+
+  test "should have many articles" do
+    assert_respond_to @user, :articles
+  end
+end