@Test
public void testUnregisterTracker() {

    ReadyTracker tracker = mock(ReadyTracker.class);
    ReadyServiceImpl rs = new ReadyServiceImpl();
    rs.markReady(new ReadyMarker("foo", "id"));
    rs.registerTracker(tracker, new ReadyMarkerFilter());
    verify(tracker).onReadyMarkerAdded(isA(ReadyMarker.class));
    rs.unregisterTracker(tracker);
    verify(tracker).onReadyMarkerRemoved(isA(ReadyMarker.class));
    verifyNoMoreInteractions(tracker);
}