def test_protocolNone(self):
        """
        If the transport has no support for protocol negotiation (returns None
        for negotiatedProtocol), HTTP/1.1 is assumed.
        """
        b = StringTransport()
        b.negotiatedProtocol = None
        negotiatedProtocol = self._negotiatedProtocolForTransportInstance(b)
        self.assertEqual(negotiatedProtocol, b'http/1.1')

        If the transport has no support for protocol negotiation (returns None
        for negotiatedProtocol), HTTP/1.1 is assumed.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_http.py