def test_order(self):
        assert (event.Priority.PRE_CORE
                > event.Priority.CORE
                > event.Priority.POST_CORE
                > event.Priority.PRE_DEFAULT
                > event.Priority.DEFAULT
                > event.Priority.POST_DEFAULT)
def test_disk_usage_sensor_is_stateless():
    sensor = disk_usage.DiskUsage()
    ok_([] != sensor.measure())