our junior and infant testings are open, anyone can watch.
Adult gradings are closed. Only the grade testing, and the grading panel are in there, with maybe one or two senior grades. That's all.
I prefer it that way (mainly because when I'm on the mat during the children's testings I hate being looked at - even though I'm not doing it) because there's no distractions. I also like the atmosphere better, feels like I'm there to do something serious.
Also, I think our gradings have a tendency to look fairly brutal, even at lower grades. I've seen people come out crying or shaking because they are fairly physical. We are encouraged to do techniques hard, (but not to hurt) and show a lot of aggression. If the juniors or parents saw it, I think they wouldn't let their children go up into the next class!