def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        else:
            ret = self[key] = self.default_factory(name=key)
            return ret
def test_base_class_get_change_list_for_accepting_suggestion_raises_error(
            self):
        with self.assertRaisesRegex(
            NotImplementedError,
            'Subclasses of BaseSuggestion should implement '
            'get_change_list_for_accepting_suggestion.'):
            self.base_suggestion.get_change_list_for_accepting_suggestion()