def METHOD_NAME(self):
    self.createMessage("new")
    self.mbox = mailbox.Maildir(test_support.TESTFN)
    self.assertTrue(len(self.mbox) == 1)
    msg = self.mbox.next()
    self.assertTrue(msg is not None)
    msg.fp.close()
    self.assertTrue(self.mbox.next() is None)
    self.assertTrue(self.mbox.next() is None)