mock instance is null after @Mock annotation

问题:

I try to run this test:

    @Mock IRoutingObjHttpClient routingClientMock;
    @Mock IRoutingResponseRepository routingResponseRepositoryMock;


    @Test
    public void testSendRoutingRequest() throws Exception {
        CompleteRoutingResponse completeRoutingResponse = new CompleteRoutingResponse();
        completeRoutingResponse.regression_latencyMillis = 500L;

        Mockito.when(routingClientMock.sendRoutingRequest(any(RoutingRequest.class))).thenReturn(completeRoutingResponse);

        RoutingObjHttpClientWithReRun routingObjHttpClientWithReRun = new RoutingObjHttpClientWithReRun
                (routingClientMock, routingResponseRepositoryMock);

...
    }

but I get NullPointerException for:

Mockito.when(routingClientMock.

what am i missing?

回答1:

When you want to use the @Mock annotation you should use the MockitoJUnitRunner

@RunWith(MockitoJUnitRunner.class)
public class MockitoTest {

    @Mock
    private IRoutingObjHttpClient routingClientMock;

    @Test
    public void testSendRoutingRequest() throws Exception {
        // ...
    }

}

See also this tutorial.

回答2:

You have three options for activating the @Mock annotation. IMHO using the MockitoRule is the best one, because it lets you still choose another runner like e.g. Parameterized.

Use the MockitoRule

public class MockitoTest {

  @Mock
  private IRoutingObjHttpClient routingClientMock;

  @Rule
  public MockitoRule rule = MockitoJUnit.rule();

  @Test
  public void testSendRoutingRequest() throws Exception {
    // ...
  }
}

Use the MockitoJUnitRunner

@RunWith(MockitoJUnitRunner.class)
public class MockitoTest {

  @Mock
  private IRoutingObjHttpClient routingClientMock;

  @Test
  public void testSendRoutingRequest() throws Exception {
    // ...
  }
}

Call MockitoAnnotations.initMocks(this) explicitly. This can be done in qn @Before method, in your own runner or in an own rule.

public class MockitoTest {

  @Mock
  private IRoutingObjHttpClient routingClientMock;

  @Before
  public void createMocks() {
    MockitoAnnotations.initMocks(this);
  }

  @Test
  public void testSendRoutingRequest() throws Exception {
    // ...
  }
}

回答3:

It can also be an import problem, so make sure you have the appropriate imported package.

For example, the "org.easymock" package also does have an annotation called @Mock, which of course, won't work with Mockito specific setup.

回答4:

1. You should use @RunWith(SpringJUnit4ClassRunner.class) at your class
2. You have to call MockitoAnnotations.initMocks(this); in @Before method

回答5:

Try to to check if the method that you are calling is a final method or not.

Mockito cannot mock the final method. https://github.com/mockito/mockito/wiki/FAQ

回答6:

If you are also using PowerMock then

@RunWith(MockitoJUnitRunner.class)

can be replaced with

@RunWith(PowerMockRunner.class)

This will activate your @Mocks and enable the PowerMock functionality.