What is the difference between @Mock, @MockBean, and @InjectMocks? @Mock, @MockBean और @InjectMocks में क्या अंतर है?

@Mock (Mockito) creates a mock object for use in plain unit tests that don't load any Spring context; it's paired with @ExtendWith(MockitoExtension.class). @InjectMocks creates an instance of the class under test and automatically injects the fields annotated with @Mock into it via constructor, setter, or field injection.

@MockBean is Spring Boot's test-specific annotation: it creates a Mockito mock and replaces the real bean of that type in the Spring application context, used inside @SpringBootTest or a slice test when you need the context to start but want to stub out one dependency (e.g. an external API client) rather than use the real implementation.

// Pure unit test
@ExtendWith(MockitoExtension.class)
class OrderServiceTest {
    @Mock private PaymentGateway paymentGateway;
    @InjectMocks private OrderService orderService;
}

// Spring context test with one dependency mocked
@WebMvcTest(OrderController.class)
class OrderControllerTest {
    @MockBean private OrderService orderService;
}