Tukukkk

I have the following class that contains a member variable, but Mockito can't seem to mock the member variable's methods. Below is my System Under Test:

public class MessageConsumer {



    private ConsumerResponse consumerResponse;

    private NotificationConsumer notificationConsumer;



    @Scheduled(cron = "${com.example.value}")

    public void fetch() {

        consumerResponse = notificationConsumer.fetchWithReturnConsumerResponse(); //no exception thrown on this line at all -- but could this be the cause of the problem in the test?

        System.out.println("consumerResponse's responseCode: " + consumerResponse.getResponseCode()); // NullPointerException thrown here

    }



    public ConsumerResponse setConsumerResponse(ConsumerResponse consumerResponse) {

        this.consumerResponse = consumerResponse;

    }



    public ConsumerResponse getConsumerResponse() {

        return consumerResponse;

    }

}

And the following is the relevant JUnit test for the class:

@SpringBootTest

@RunWith(MockitoJUnitRunner.class)

public class MessageConsumerTest {



    @Mock

    private ConsumerResponse consumerResponse;



    @InjectMocks

    private MessageConsumer messageConsumer;



    @Before

    public void setup() {

        MockitoAnnotations.initMocks(this);

    }



    //Failing unit test

    @Test

    public void getResponseCodeShouldReturn200() {

        Mockito.when(consumerResponse.getResponseCode()).thenReturn("200");

        messageConsumer.fetch()

    }



}

As you can see, I've mocked the ConsumerResponse consumerResponse variable to return "200" when the consumerResponse.getResponseCode() method gets invoked. Instead, I'm getting a NullPointerException.

I'm pretty sure I mocked the member variable correctly and initialized it appropriately (initMocks). I've spent days trying to figure this out. Where am I going wrong?

As NotificationConsumer is also an external dependency for this class, you have to also mock this class as otherwise consumerResponse = notificationConsumer.fetchWithReturnConsumerResponse(); will result into null within your test as you didn't mock the NotificationConsumer. In addition I would suggest not to use @SpringBootTest within this unit test as this annotation will boot the whole Spring context. The following snippet should help you:

@RunWith(MockitoJUnitRunner.class)

public class MessageConsumerTest {



    @Mock

    private ConsumerResponse consumerResponse;



    @Mock

    private NotificationConsumer notificationConsumer;



    @InjectMocks

    private MessageConsumer messageConsumer;



    @Before

    public void setup() {

        MockitoAnnotations.initMocks(this);

    }



    @Test

    public void getResponseCodeShouldReturn200() {

        Mockito.when(notificationConsumer.fetchWithReturnConsumerResponse()).thenReturn(consumerResponse);

        Mockito.when(consumerResponse.getResponseCode()).thenReturn("200");

        messageConsumer.fetch();

    }



}