def test_notify_observers(self):
notifier = Notifier()
observer1 = Mock(spec=Observer)
observer2 = Mock(spec=Observer)
notifier.register_observer(observer1)
notifier.register_observer(observer2)
notifier.notify_observers()
observer1.notify.assert_called_once_with(notifier=notifier)
observer2.notify.assert_called_once_with(notifier=notifier)
def test_register_non_observer(self):
notifier = Notifier()
non_observer = Mock()
notifier.register_observer(non_observer)
