'If the user requests a service that we don\'t support, the
authentication should fail.'

def test_failIfUnknownService(self):

    packet = ((((NS('foo') + NS('')) + NS('password')) + chr(0)) + NS('foo'))
    self.authServer.clock = task.Clock()
    d = self.authServer.ssh_USERAUTH_REQUEST(packet)
    return d.addCallback(self._checkFailed)
