def test_connectionLost(self):
        """
        When disconnection occurs while commands are still outstanding, the
        commands fail.
        """
        d1 = self.proto.get(b"foo")
        d2 = self.proto.get(b"bar")
        self.transport.loseConnection()
        done = DeferredList([d1, d2], consumeErrors=True)

        def checkFailures(results):
            for success, result in results:
                self.assertFalse(success)
                result.trap(ConnectionDone)

        return done.addCallback(checkFailures)

        When disconnection occurs while commands are still outstanding, the
        commands fail.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_memcache.py