def test_nonIntegerUIDVALIDITY(self):
        """
        If the server returns a non-integer UIDVALIDITY value in its response to
        a I{SELECT} or I{EXAMINE} command, the L{Deferred} returned by
        L{IMAP4Client.select} or L{IMAP4Client.examine} fails with
        L{IllegalServerResponse}.
        """
        d = self._examineOrSelect()
        self._response(b'* OK [UIDVALIDITY foo] UIDs valid')
        self.failureResultOf(d, imap4.IllegalServerResponse)

        If the server returns a non-integer UIDVALIDITY value in its response to
        a I{SELECT} or I{EXAMINE} command, the L{Deferred} returned by
        L{IMAP4Client.select} or L{IMAP4Client.examine} fails with
        L{IllegalServerResponse}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/mail/test/test_imap.py