Unit testing anonymous inner classes as event listener

Unit.java

public class Unit {

    public Unit(EventDispatcher dispatcher) {

        dispatcher.addHandler(MyEvent.class, new IEventHandler() {			
            public void onEvent(MyEvent event) {
	        // some behavior
            }			
        });
		
    }

}

UnitTest.java

public class UnitTest {

    @Test
    public void whenDispatcherTriggersMyEventThenIExpectBehaviour() {
        EventDispatcher mockedDispatcher = mock(EventDispatcher.class);
        new Unit(mockedDispatcher);

        ArgumentCaptor<IEventHandler> myEventHandlerCaptor = ArgumentCaptor.forClass(IEventHandler.class);
        verify(mockedDispatcher).addHandler(eq(MyEvent.class), myEventHandlerCaptor.capture());

        IEventHandler myEventHandler = myEventHandlerCaptor.getValue();		
        MyEvent mockedEvent = mock(MyEvent.class);

        myEventHandler.onEvent(mockedEvent);

        // verify behavior
    }

}

Let's put 1, 3 and 4 aside, they doesn't matter at all right now.
I made up this example and quickly wrote it in the textarea to show some concrete testworthy behavior. Let's exchange ConnectionManager with ServerMonitor and say it needs to display current connections to the user. The pattern doesn't change.

Its all about naming things ;-) #ServerObserver

@jmaicher
thanks man,this one helped me ..