M04 Q43 What are the differences between @MockBean and @Mock?

@Mock annotation comes from Mockito Framework which allows for easy Mock creation. This annotation is used by MockitoJUnitRunner, each field annotated with it will have Mock for specified class created. This annotation does not inject mocks into tested class on itself, to use injection you need to have target class annotated with @InjectMocks annotation.

@MockBean annotation comes from spring-boot-test, it creates Mockito Mock and also injects it into Application Context created by @SpringBootTest. All beans which refers to mocked class via @Autowired will get this mock injected instead of real class.

Main difference between @MockBean and @Mock annotation is that @MockBean creates mock and injects it into Application Context, while @Mock annotation only creates it, if you want to inject it, you can do it manually or with @InjectMocks annotation, however injection is being done to the class not whole Application Context.