Obviously, I'll feel embarassed/frustrated if I don't do well ... even if I pass. My real concern, however, is that I'll feel that I didn't represent my sensei well after he has placed his confidence in me. Senseis are essentially putting their personal "seal of approval" on a student when they have him test, and I think that most of us feel pressure to live up to that vote of confidence. I'll feel really bad if I don't have as good a test as I think that I can, knowing that I didn't have the time to train the way that I should have.
I guess that the proof will be in a pre-test.
If your sensei puts his "seal of approval" and you fail, the fault is his.