How can I mock methods of @InjectMocks class?

Question

For example I have handler:

@Component
public class MyHandler {

  @AutoWired
  private MyDependency myDependency;

  public int someMethod() {
    ...
    retur         


        

Answer 1

In your code, you are not testing MyHandler at all. You don't want to mock what you are testing, you want to call its actual methods. If MyHandler has dependencies, you mock them.

Something like this:

public interface MyDependency {
  public int otherMethod();
}

public class MyHandler {
  @AutoWired
  private MyDependency myDependency;

  public void someMethod() {
    myDependency.otherMethod();
  }
}

And in test:

private MyDependency mockDependency;
private MyHandler realHandler;

@Before
public void setup() {
   mockDependency = Mockito.mock(MyDependency.class);
   realHandler = new MyHandler();
   realhandler.setDependency(mockDependency); //but you might Springify this 
}

@Test
public void testSomeMethod() {

  //specify behaviour of mock
  when(mockDependency.otherMethod()).thenReturn(1);

  //really call the method under test
  realHandler.someMethod();
}

The point is to really call the method under test, but mock any dependencies they may have (e.g. calling method of other classes)

If those other classes are part of your application, then they'd have their own unit tests.

NOTE the above code could be shortened with more annotations, but I wanted to make it more explicit for the sake of explanation (and also I can't remember what the annotations are :) )