'Sending an unimplemented command is responded to with a 500.'

def test_SMTPUnknownCommand(self):

    s = smtp.SMTP()
    t = StringTransport()
    s.makeConnection(t)
    s.lineReceived('DOAGOODTHING')
    s.connectionLost(error.ConnectionDone())
    self.assertIn('500    Command    not    implemented', t.value())
