Testing nerves are normal, some people freeze during school exams but know the material, thats just life. I'm now a 2nd Dan and when we have colour belt testing I see students that are almost making themselves sick. When I try too calm them down I hear the same thing "your a black belt your passed this problem". I personally figured that the butterflies in my stomach are testing for the same belt and can they kick up a fuss. But I would not be allowed too test if my clubs Master did not think I was ready. All I can do while testing is give it all I can...oh and remember too breath.