def test_observer_executes_when_notified(self):
class DummyObserver(Observer):
def on_change(self):
self.test_value += 1
obs = DummyObserver()
obs.test_value = 1
obs2 = DummyObserver()
obs2.test_value = 1
self.assertEqual(obs.test_value, 1)
obs.notify()
self.assertEqual(obs.test_value, 2)
obs.notify()
self.assertEqual(obs.test_value, 3)
self.assertEqual(obs2.test_value, 1)
able = Observable()
able.register_observer(obs)
self.assertEqual(obs.test_value, 4)
able.notify_observers()
self.assertEqual(obs.test_value, 5)
self.assertEqual(obs2.test_value, 1)
def test_observer_receives_observable_signals(self):
obs = Observer()
obs2 = Observer()
able = Observable()
able.register_observer(obs)
self.assertIn(obs, able._observers)
self.assertNotIn(obs2, able._observers)
def test_observable_keeps_no_duplicates(self):
obs = Observer()
able = Observable()
self.assertEqual(len(able._observers), 0)
able.register_observer(obs)
self.assertEqual(len(able._observers), 1)
able.register_observer(obs)
self.assertEqual(len(able._observers), 1)
able.register_observer(Observer())
self.assertEqual(len(able._observers), 2)
able.unregister_observer(obs)
self.assertEqual(len(able._observers), 1)