def test_listOneMessage(self):
        mailbox = mail.maildir.StringListMailbox(["abc", "ab", "a"])
        self.assertEqual(mailbox.listMessages(0), 3)
        self.assertEqual(mailbox.listMessages(1), 2)
        self.assertEqual(mailbox.listMessages(2), 1)
L{StringListMailbox.listMessages} returns the length of the message at
dataset/ETHPy150Open kuri65536/python-for-android/python-modules/twisted/twisted/mail/test/test_mail.py/StringListMailboxTests.test_listOneMessage