def test_nextProtocolMechanismsALPNIsSupported(self):
        """
        When ALPN is available on a platform, protocolNegotiationMechanisms
        includes ALPN in the suported protocols.
        """
        supportedProtocols = sslverify.protocolNegotiationMechanisms()
        self.assertTrue(
            sslverify.ProtocolNegotiationSupport.ALPN in
            supportedProtocols
        )

        When ALPN is available on a platform, protocolNegotiationMechanisms
        includes ALPN in the suported protocols.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_sslverify.py