BAEL-6830 (#14722)

* BAEL-6830 initial commit

* BAEL-6830 clean up code

testing-modules/mockito-2/src/main/java/com/baeldung/constructor/User.java

@@ -0,0 +1,18 @@
+package com.baeldung.constructor;
+
+public class User {
+
+    private final UserService userService;
+
+    public User() {
+        this.userService = new UserService();
+    }
+
+    public User(String userName) {
+        this.userService = new UserService(userName);
+    }
+
+    public String getUserName(){
+        return userService.getUserName();
+    }
+}

testing-modules/mockito-2/src/main/java/com/baeldung/constructor/UserService.java

@@ -0,0 +1,18 @@
+package com.baeldung.constructor;
+
+public class UserService {
+
+    private final String userName;
+
+    public UserService(String userName) {
+        this.userName = userName;
+    }
+
+    public UserService() {
+        this.userName = "Unknown";
+    }
+
+    public String getUserName(){
+        return this.userName;
+    }
+}

testing-modules/mockito-2/src/test/java/com/baeldung/constructor/UserServiceUnitTest.java

@@ -0,0 +1,55 @@
+package com.baeldung.constructor;
+
+import static org.mockito.Mockito.when;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.mockito.MockedConstruction;
+import org.mockito.Mockito;
+
+class UserServiceUnitTest {
+
+    @Test
+    void whenConstructorInvokedWithInitializer_ThenMockObjectShouldBeCreated(){
+        try(MockedConstruction<UserService> mockUserService = Mockito.mockConstruction(UserService.class,(mock,context)-> when(mock.getUserName()).thenReturn("John Doe"))){
+            User user = new User();
+            Assertions.assertEquals(1,mockUserService.constructed().size());
+            Assertions.assertEquals("John Doe",user.getUserName());
+        }
+    }
+
+    @Test
+    void whenConstructorInvokedWithoutInitializer_ThenMockObjectShouldBeCreatedWithNullFields(){
+        try(MockedConstruction<UserService> mockUserService = Mockito.mockConstruction(UserService.class)){
+            User user = new User();
+            Assertions.assertEquals(1,mockUserService.constructed().size());
+            Assertions.assertNull(user.getUserName());
+        }
+    }
+
+    @Test
+    void whenConstructorInvokedWithParameters_ThenMockObjectShouldBeCreated(){
+        try(MockedConstruction<UserService> mockUserService = Mockito.mockConstruction(UserService.class,(mock, context) -> when(mock.getUserName()).thenReturn("John Doe"))){
+            User user = new User("Mike");
+            Assertions.assertEquals(1,mockUserService.constructed().size());
+            Assertions.assertEquals("John Doe",user.getUserName());
+        }
+    }
+
+    @Test
+    void whenMultipleConstructorsInvoked_ThenMultipleMockObjectsShouldBeCreated(){
+        try(MockedConstruction<UserService> mockUserService = Mockito.mockConstruction(UserService.class)){
+            User user = new User();
+            User secondUser = new User();
+            User thirdUser = new User("Mike");
+
+            when(mockUserService.constructed().get(0).getUserName()).thenReturn("John Doe");
+            when(mockUserService.constructed().get(1).getUserName()).thenReturn("Steve Smith");
+
+            Assertions.assertEquals(3,mockUserService.constructed().size());
+            Assertions.assertEquals("John Doe",user.getUserName());
+            Assertions.assertEquals("Steve Smith",secondUser.getUserName());
+            Assertions.assertNull(thirdUser.getUserName());
+        }
+    }
+}