At our school, its emphasized that if you test, and don't do well (forget a part of a kata, don't perform on belt level, etc), you will fail. And it has happened to both of my sons, now 8 and 12. But from it, they learn to accept failure and push through them, to not give up no matter what. I know some schools in this local area, where when you test, no matter how bad you do, you're still promoted, based on the fact that you are prob. nervous and they have seen you train in class. In our setting, I do get nervous. But I try to use my nervousness to push myself harder, and usually, my tests are great. But if i was in a setting where I was only testing as part of the belt promotion, and I knew I was going to pass regardless, why be nervous?