def test_wrappingProtocolHandshakeListener(self):
        """
        Our L{_WrappingProtocol} should be an L{IHandshakeListener} if
        the C{wrappedProtocol} is.
        """
        handshakeListener = TestHandshakeListener()
        wrapped = endpoints._WrappingProtocol(None, handshakeListener)
        self.assertTrue(interfaces.IHandshakeListener.providedBy(wrapped))

        Our L{_WrappingProtocol} should be an L{IHandshakeListener} if
        the C{wrappedProtocol} is.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_endpoints.py