public class ArticleManager {
    private User user;
    private ArticleDatabase database;

    public ArticleManager(User user, ArticleDatabase database) {
        super();
        this.user = user;
        this.database = database;
    }

    public void initialize() {
        database.addListener(new ArticleListener());
    }
}

/**
*This class can be constructed
*via Mockito and its dependencies can be fulfilled
*with mock objects as demonstrated by the following code snippet.
**/


@RunWith(MockitoJUnitRunner.class)
public class ArticleManagerTest  {

       @Mock ArticleCalculator calculator;
       @Mock ArticleDatabase database;
       @Mock User user;

       @Spy private UserProvider userProvider = new ConsumerUserProvider();

        //creates an instance of ArticleManager and injects the mocks into it

       @InjectMocks private ArticleManager manager;

       @Test public void shouldDoSomething() {
           // calls addListener with an instance of ArticleListener
           manager.initialize();

           // validate that addListener was called
           verify(database).addListener(any(ArticleListener.class));
       }
}