def test_missingConfiguration(self):
        """
        A missing nameserver configuration file results in no server information
        being loaded from it (ie, not an exception) and a default server being
        provided.
        """
        resolver = client.Resolver(resolv=self.mktemp(), reactor=Clock())
        self.assertEqual([("127.0.0.1", 53)], resolver.dynServers)

        A missing nameserver configuration file results in no server information
        being loaded from it (ie, not an exception) and a default server being
        provided.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/test/test_client.py