'Connect the clientFactory, and check the timeout on the request.'

def _timeoutTest(self, onDone, clientFactory):

    clock = task.Clock()
    client = clientFactory.buildProtocol(address.IPv4Address('TCP', 'example.net', 25))
    client.callLater = clock.callLater
    t = StringTransport()
    client.makeConnection(t)
    t.protocol = client
    def check(ign):
        self.assertEqual(clock.seconds(), 0.5)
    d = self.assertFailure(onDone, smtp.SMTPTimeoutError).addCallback(check)
    clock.advance(0.1)
    clock.advance(0.4)
    return d
