@Test
public void testAttributeAdded() {

  HttpSessionAttributeListener listener = mock(HttpSessionAttributeListener.class);
  descriptor.addHttpSessionAttributeListener(listener);
  notifier.attributeAdded(session, "Test", "value");
  verify(listener).attributeAdded(any(HttpSessionBindingEvent.class));
  HttpSessionBindingListener bindingListener = mock(HttpSessionBindingListener.class);
  notifier.attributeAdded(session, "Test", bindingListener);
  verify(listener, times(2)).attributeAdded(any(HttpSessionBindingEvent.class));
  verify(bindingListener).valueBound(any(HttpSessionBindingEvent.class));
}