'Test the two forms of list: with a message index number, which should
return a short-form response, and without a message index number, which
should return a long-form response, one line per message.'

def testLIST(self):

    p = self.pop3Server
    s = self.pop3Transport
    p.lineReceived('LIST    1')
    self._flush()
    self.assertEqual(s.getvalue(), '+OK    1    44\r\n')
    s.truncate(0)
    p.lineReceived('LIST')
    self._flush()
    self.assertEqual(s.getvalue(), '+OK    1\r\n1    44\r\n.\r\n')
