def test_stringDescription(self):
        """
        L{serverFromString} returns a L{TCP6ServerEndpoint} instance with a
        'tcp6' endpoint string description.
        """
        ep = endpoints.serverFromString(
            MemoryReactor(), "tcp6:8080:backlog=12:interface=\:\:1")
        self.assertIsInstance(ep, endpoints.TCP6ServerEndpoint)
        self.assertIsInstance(ep._reactor, MemoryReactor)
        self.assertEqual(ep._port, 8080)
        self.assertEqual(ep._backlog, 12)
        self.assertEqual(ep._interface, '::1')

        L{serverFromString} returns a L{TCP6ServerEndpoint} instance with a
        'tcp6' endpoint string description.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_endpoints.py