def test_invalidCommand(self):
        """
        When an unknown command is sent directly (not through public API), the
        server answers with an B{ERROR} token, and the command fails with
        L{NoSuchCommand}.
        """
        d = self.proto._set(b"egg", b"foo", b"bar", 0, 0, b"")
        self.assertEqual(self.transport.value(), b"egg foo 0 0 3\r\nbar\r\n")
        self.assertFailure(d, NoSuchCommand)
        self.proto.dataReceived(b"ERROR\r\n")
        return d

        When an unknown command is sent directly (not through public API), the
        server answers with an B{ERROR} token, and the command fails with
        L{NoSuchCommand}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_memcache.py