@Test
public void listenAndFireWorks() throws Exception {

  ListenerManager listeners = new ListenerManager();
  IntListener intListener = new IntListener();
  IntValueProperty intProperty = new IntValueProperty(10);
  listeners.listenAndFire(intProperty, intListener);
  assertThat(intListener.myInvalidationCount).isEqualTo(1);
  intProperty.set(20);
  assertThat(intListener.myInvalidationCount).isEqualTo(2);
}