def test_makeDirectory(self):
        """
        L{ftp.FTPClient.makeDirectory} issues a I{MKD} command and returns a
        L{Deferred} which is called back with the server's response if the
        directory is created.
        """
        self._testLogin()

        d = self.client.makeDirectory("/spam")
        self.assertEqual(self.transport.value(), b'MKD /spam\r\n')
        self.client.lineReceived(b'257 "/spam" created.')
        return d.addCallback(self.assertEqual, ['257 "/spam" created.'])

        L{ftp.FTPClient.makeDirectory} issues a I{MKD} command and returns a
        L{Deferred} which is called back with the server's response if the
        directory is created.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_ftp.py