mocking of callback function

callbackMocking.java

ArrayList<Entity> list = new ArrayList<Entity>();
someObject.someMethod(p1, p2, new InnerInterface<Entity>() {
        @Override
        public boolean onEntry(Entity entity) 
        {
            //some logic
            legs.add(entry);
            return true;
        }
    });
    
    doAnswer(
    new Answer<Void>() {
        @Override
        public Void answer(final InvocationOnMock invocation) throws Throwable {
            InnerInterface<Entity> callback = (InnerInterface<Entity>) invocation.getArguments()[2];
                callback.onEntry(strategyLeg);
                return null;
            }
        }
    ).when(mockObject).someMethod(any(P1Param.class), any(P2Param.class), any(InnerInterface.class));
    
    @Test
        public void testDoSomethingAsynchronouslyUsingArgumentCaptor() {
		// Let's call the method under test
		dummyCaller.doSomethingAsynchronously();
 
		final List<String> results = Arrays.asList("One", "Two", "Three");
 
		// Let's call the callback. ArgumentCaptor.capture() works like a matcher.
		verify(mockDummyCollaborator, times(1)).doSomethingAsynchronously(
				dummyCallbackArgumentCaptor.capture());
 
		// Some assertion about the state before the callback is called
		assertThat(dummyCaller.getResult().isEmpty(), is(true));
 
		// Once you're satisfied, trigger the reply on callbackCaptor.getValue().
		dummyCallbackArgumentCaptor.getValue().onSuccess(results);
 
		// Some assertion about the state after the callback is called
		assertThat(dummyCaller.getResult(), is(equalTo(results)));
	}