Mockito: mocking a method of same class called by method under test when using @InjectMocks

Question

I have a class I want to test that has several external dependencies, and a couple internal methods. I would like to write a test for MethodA, but not have Method A's internal call to MethodB to actually exercise MethodB. I'd like to mock/stub MethodB and return something specific instead. Usually I'd use when/thenReturn but it doesn't behave like I expect - it actually jumps into Method B while creating the mock itself.

MyService.java

@Service
public class MyService {

  @Autowired
  private ServiceA serviceA;

  @Autowired
  private ServiceB serviceB;

    public SomeObject methodA() {
      // some logic using serviceA.method and serviceB.method that creates "output"
      SomeObject someObject = methodB(output);
      return someObject;
    }

    public SomeObject methodB(SomeObject someObject) {
      // deep mysteries done here to someObject
      return someObject 
    }
}

MyServiceTest.java

public class MyServiceTest {

  @Mock
  private ServiceA serviceA;

  @Mock
  private ServiceB serviceB;

  @InjectMocks
  private MyService myService;

  @Before
  public void setUp() throws Exception {
    MockitoAnnotations.initMocks(this);
  }

  @Test
  public void methodATest() {
    when(serviceA.method()).thenReturn(stuff);
    when(serviceB.method()).thenReturn(otherStuff);

    // here is what I would like to do
    when(myService.methodB()).thenReturn(mockedSomeObject); //<- doesn't work

    assertThat(myService.methodA().getSomeObjectProperty())
        .isEqualTo("property");
  }
}

I've looked at solutions that manually mock the MyService class with Mockito.mock(MyService.class), but (as the above example is obviously contrived) my actual class has quite a few external dependencies and I'd prefer a solution that still allows me to mock the service using @Mock for the @Autowired dependencies and @InitMocks for the class under test, unless it's simply not possible.

I've tried:

Mockito.doReturn(mockedSomeObject).when(myService.methodB(any(SomeObject.class));

but that also steps into MethodB when creating the mock for that method, which shouldn't be happening.

Thanks in advance for the help!

Answer 1

Try Adding @Spy to your InjectMocks and use the object to "expect" them in a slightly different syntax.

import org.mockito.Spy;

 @InjectMocks
 @Spy
 private MyService myService; 

And now mock the service call

 Mockito.doReturn(mockedSomeObject).when(myService).methodB();

Also change the other mock call to this

Mockito.doReturn(stuff).when(serviceA).method();
Mockito.doReturn(otherStuff).when(serviceB).method();

Answer 2

You need to mark your object as Spy or explicitly create a Spy object for it using MyClass objA=null; MyClass spy_objA=Powermockito.spy(objA) doReturn(what_you_want).when(spy_objA).method()

Edit: Can find a similar question you may want to check How to mock another method in the same class which is being tested?