How to mock the view in the MVC integration testing using JUnit and EasyMock

Question

I would like to mock a view implementation of the MVC design pattern . I have implemented the MVP (another MVC variation), and would like to test if the certain methods in the view get called correctly by the controller when a state change happens on the model. The following shows the sequence of method calls on the model , controller and view .

Model:

model.setProperty("newProperty");

Controller:

@Override
    public void propertyChange(PropertyChangeEvent evt) {
        for (View view : views) {
            view.modelPropertyChange(evt);
        }
    }

View: This result to the view being called as like:

@Override
    public void modelPropertyChange(PropertyChangeEvent evt) {
        if ("Property".equals(evt.getPropertyName())) {
            updateView();
        }
    }

Question: How do verify(using EasyMock in the JUnit test), the expected order of method(with valid argument(s)) execution? I expect view.modelPropertyChange(evt) to get called and the expect view.isViewUpdated() to return true on the view object. How do I say that in my JUnit test? Please help!

Answer 1

@RunWith(JUnit4.class)
public class ControllerTest {
  @Test
  public void updateView() {
    PropertyChangeEvent evt = new PropertyChangeEvent( ... );
    View mockView = EasyMock.createMock(View.class);
    mockView.modelPropertyChange(evt);
    EasyMock.replay(mockView);

    Controller controller = new Controller( ... );
    controller.propertyChange(mockView);
    EasyMock.verify(mockView);
  }
}

Note that the Controller.propertyChange() doesn't call View.isViewUpdated() so there is no need to mock isViewUpdated . You would test isViewUpdated in a test for the View class.

If propertyChange did call isViewUpdated then you would add the following call before EasyMock.replay() :

EasyMock.expect(mockView.isViewUpdated()).andReturn(true);

Note that EasyMock.createMock() does not enforce that the mocked methods be called in the order they were mocked. If you want the method order to be enforced, use EasyMock.createStrictMock()