'L{MaildirMailbox.appendMessage} returns a L{Deferred} which fires when
the message has been added to the end of the mailbox.'

def test_append(self):

    mbox = mail.maildir.MaildirMailbox(self.d)
    messages = []
    for i in range(1, 11):
        temp = tempfile.TemporaryFile()
        temp.write(('X' * i))
        temp.seek(0, 0)
        messages.append(temp)
        self.addCleanup(temp.close)
    d = self._appendMessages(mbox, messages)
    d.addCallback(self._cbTestAppend, mbox)
    return d
