def test_unsupportedScheme(self):
        """
        L{Agent.request} returns a L{Deferred} which fails with
        L{SchemeNotSupported} if the scheme of the URI passed to it is not
        C{'http'}.
        """
        return self.assertFailure(
            self.agent.request(b'GET', b'mailto:alice@example.com'),
            SchemeNotSupported)

        L{Agent.request} returns a L{Deferred} which fails with
        L{SchemeNotSupported} if the scheme of the URI passed to it is not
        C{'http'}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_agent.py