def test_tlsWithDefaults(self):
        """
        When passed a C{tls:} strports description without extra arguments,
        L{clientFromString} returns a client endpoint whose context factory is
        initialized with default values.
        """
        reactor = object()
        endpoint = endpoints.clientFromString(reactor, b'tls:example.com:443')
        creator = connectionCreatorFromEndpoint(reactor, endpoint)
        self.assertEqual(creator._hostname, u'example.com')
        self.assertEqual(endpoint._wrappedEndpoint._hostBytes, b'example.com')

        When passed a C{tls:} strports description without extra arguments,
        L{clientFromString} returns a client endpoint whose context factory is
        initialized with default values.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_endpoints.py