def test_clear_no_notifications_if_already_empty(self):
# test no notifications are emitted if the set is already
# empty.
notifier = mock.Mock()
ts = TraitSet(notifiers=[notifier])
ts.clear()
notifier.assert_not_called()
def test_clear(self):
ts = TraitSet({1, 2, 3}, item_validator=int_validator,
notifiers=[self.notification_handler])
ts.clear()
self.assertEqual(self.removed, {1, 2, 3})
self.assertEqual(self.added, set())