def test_unsupportedCommand(self):
        """
        L{imap4.IMAP4Server} responds to an unsupported command with a
        C{BAD} response.
        """
        self.server.lineReceived(b"001 HULLABALOO")
        self.assertEqual(self.transport.value(),
                         b"001 BAD Unsupported command\r\n")

        L{imap4.IMAP4Server} responds to an unsupported command with a
        C{BAD} response.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/mail/test/test_imap.py