def test_cleanReactorReturnsSelectableStrings(self):
        """
        The Janitor returns string representations of the selectables that it
        cleaned up from the reactor cleanup method.
        """
        class Selectable(object):
            """
            A stub Selectable which only has an interesting string
            representation.
            """
            def __repr__(self):
                return "(SELECTABLE!)"

        reactor = StubReactor([], [Selectable()])
        jan = _Janitor(None, None, reactor=reactor)
        self.assertEqual(jan._cleanReactor(), ["(SELECTABLE!)"])

        The Janitor returns string representations of the selectables that it
        cleaned up from the reactor cleanup method.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/trial/test/test_util.py