What is the Difference between @Mock, @MockBean and Mockito.mock()?

@Mock, Mockito.mock(), and @MockBean are all related to creating mock objects for testing, but they are used in different contexts and frameworks. Let’s break down the differences:

What is @Mock?

• @Mock is an annotation provided by the Mockito framework.
• It is used in conjunction with a testing framework like JUnit or TestNG.
• @Mock is used to create a mock object, but you need to initialize it before using it in tests. Example:

   import org.mockito.Mock;

   // ...

   @Mock
   private MyService myService;

What is Mockito.mock()?

• Mockito.mock() is a method provided by the Mockito framework.
• It is used to manually create a mock object when you are not using annotations or when you need more control over the creation of the mock.
• It is often used in conjunction with JUnit or TestNG tests. Example:

   import static org.mockito.Mockito.mock;

   // ...

   MyService myService = mock(MyService.class);

What is @MockBean?

• @MockBean is a Spring Boot annotation.
• It is used in integration tests (generally @SpringBootTest) to replace a real bean with a mock within the Spring context.
• @MockBean is specifically designed for use in the Spring context, allowing you to replace a real bean with a Mockito mock during the testing of Spring components. Example:

   import org.springframework.boot.test.mock.mockito.MockBean;

   // ...

   @SpringBootTest
   public class MyServiceTest {

       @MockBean
       private MyService myService;
   }

@Mock and Mockito.mock() are from the Mockito framework and are generally used in non-Spring testing scenarios. They are equivalent way to mock an object.

On the other hand, @MockBean is a Spring Boot annotation specifically designed for replacing beans with mocks in the Spring context during integration tests. Choose the one that aligns with your testing framework and context.