def test_reprableComponentized(self):
        """
        C{ReprableComponentized} has a C{__repr__} that lists its cache.
        """
        rc = components.ReprableComponentized()
        rc.setComponent(ITest, "hello")
        result = repr(rc)
        self.assertIn("ITest", result)
        self.assertIn("hello", result)

        C{ReprableComponentized} has a C{__repr__} that lists its cache.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/test/test_components.py