'L{StringListMailbox.sync} causes any messages as marked for deletion to
be permanently deleted.'

def test_sync(self):

    mailbox = mail.maildir.StringListMailbox(['foo'])
    mailbox.deleteMessage(0)
    mailbox.sync()
    mailbox.undeleteMessages()
    self.assertEqual(mailbox.listMessages(0), 0)
    self.assertEqual(mailbox.listMessages(), [0])
