def test_emptyPASS(self):
        """
        L{pop3.POP3} handles a I{PASS} command with a password equal to C{""}
        as it would any other value.
        """
        dummy = DummyPOP3()
        client = LineSendingProtocol([
            b"PASS ",
            b"QUIT"
        ])
        d = loopback.loopbackAsync(dummy, client)
        return d.addCallback(self._cbTestEmptyPASS, client, dummy)

        L{pop3.POP3} handles a I{PASS} command with a password equal to C{""}
        as it would any other value.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/mail/test/test_pop3.py