How can I achieve dependency injection with Mockito in JUnit 5?

General Discussions
1

How can I use Mockito JUnit 5 for dependency injection?

In JUnit 4, I can simply use the @RunWith(MockitoJUnitRunner.class) annotation to enable Mockito. However, in JUnit 5, there is no equivalent @RunWith annotation.

How can I achieve dependency injection with Mockito in JUnit 5?

2

Hey

To resolve your query, you can use @ExtendWith(MockitoExtension.class); this helped me resolve the issue I was facing the same as yours.

In JUnit 5, the @ExtendWith annotation is used to integrate Mockito into tests. This is the preferred way to enable Mockito extensions for dependency injection in JUnit 5.

@ExtendWith(MockitoExtension.class)
public class MyTest {

    @Mock
    private MyService myService;

    @Test
    public void testMyService() {
        when(myService.doSomething()).thenReturn("result");
        assertEquals("result", myService.doSomething());
    }
}

Hope I was able to help you :slight_smile:

3

If you prefer manual control over initialization, you can use MockitoAnnotations.openMocks(this) in the setup method, which is an alternative to @ExtendWith and initializes mock objects for JUnit 5.

public class MyTest {

    @Mock
    private MyService myService;

    @BeforeEach
    public void initMocks() {
        MockitoAnnotations.openMocks(this);
    }

    @Test
    public void testMyService() {
        when(myService.doSomething()).thenReturn("result");
        assertEquals("result", myService.doSomething());
    }
}
4

Mockito JUnit 5 allows the use of @Mock for mock objects and @InjectMocks for the class under test. These annotations work together to automatically inject the mocks into the class being tested.

@ExtendWith(MockitoExtension.class)

public class MyTest {

    @Mock
    private MyService myService;

    @InjectMocks
    private MyController myController;

    @Test
    public void testController() {
        when(myService.doSomething()).thenReturn("result");
        assertEquals("result", myController.getServiceResult());
    }
}