def test_removeFile(self):
        """
        L{ftp.FTPClient.removeFile} sends a I{DELE} command to the server for
        the indicated file and returns a Deferred which fires after the server
        sends a 250 response code.
        """
        self._testLogin()
        d = self.client.removeFile("/tmp/test")
        self.assertEqual(self.transport.value(), b'DELE /tmp/test\r\n')
        response = '250 Requested file action okay, completed.'
        self.client.lineReceived(response.encode(self.client._encoding))
        return d.addCallback(self.assertEqual, [response])

        L{ftp.FTPClient.removeFile} sends a I{DELE} command to the server for
        the indicated file and returns a Deferred which fires after the server
        sends a 250 response code.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_ftp.py