def test_interface(self):
        """
        L{client.getResolver} returns an object providing L{IResolver}.
        """
        with AlternateReactor(Clock()):
            resolver = client.getResolver()
        self.assertTrue(verifyObject(IResolver, resolver))

        L{client.getResolver} returns an object providing L{IResolver}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/test/test_client.py