Sometimes you might have to ask what you need to do to test just to clarify stuff. For instance, in my dojo there was this longstanding myth that a brown belt had to wait until the sensei told them they could test for the black belt. The fact was that a brown belt was supposed to sign up themself when they thought they were up to it. If you're somebody who believes that you need to wait until sensei tells you that you can test, than you will be waiting indefinitely if you don't get the proper information, that you're supposed to sign up yourself. Getting the proper information often involves talking to your sensei.
Gee, amazing how you seem to keep repeating yourself. Anyways...thought I'd share something from class last night. We started class off with some floor drills..moving up and down the floor, throwing various block, punches, etc. One of the combos was a step forward, downward block, upward block and then punch. My teacher made a correction on the way I was doing this. It was simply the way I should've been turning when applying the blocks, and then when I threw the punch. I made those corrections and got the nod of approval from my teacher.
Fast forward a bit later in the class. We hung the heavy bags and drilled punches. Again, he made adjustments/corrections in the way I was punching, so as to not only do it correctly, but also to generate more power. Again, after making the necessary corrections, I got the nod of approval.
I know what I need to work on in those situations, and I didn't even have to ask. My job now, is to continue to make sure I do those things correctly, from now on. It's not always what you need to know, as in physical techniques, but how you apply those things. If you're possibly testing for a higher rank, but you perform things like a lower rank, well, odds are, you probably won't get told to test. If you only show up once a week to class, odds are, until you apply yourself, get off your *** and show up 2, 3, 4+ times/week, well, hello....you're probably not going to be told to test.
Again, I'm not saying you shouldn't ask, but if you think that you have to ask each and every time, well....no, you don't.