Forgive me if I missed something, but I have read no mention so far of the fact that you're not the only one getting tested!
The granting authority (even if it's the same instructor you always have) is being tested as well.
You may also someday test in front of a person of much higher rank than your usual Sensei, who will watch quietly and hope you don't screw up.
If you pass, it proves two
things: you can learn, and your instructor can teach. This is another reason why you should not refuse a testing opportunity. It's not just an opportunity for you, it's a service you provide for your instructor.
With that in mind, forget about avoiding a boring show. Rank test is not a show, and if you're worried about spectators being bored, don't be: the ones who know what to look for won't be, and the others can entertain themselves in the lobby.