I've been training for a few years now in the same dojo and I have not yet tested for rank. I'm fine with this; I don't feel the need to test and my sensei told me that if I ever showed the desire or asked to test then my sensei would schedule for an exam.
Our dojo is pretty small (which is good for me) and I can understand the reasons for not yet being tested. The other students in my class do have ranks, but I don't think they've been tested since I joined (though I could be wrong about that).
I mostly go to learn as much as I can and to enjoy as I progress. I'm enjoying Aikido and I find the experience to be invaluable. I don't think any of us have as much interest in rank as much as just want to learn as much as we can and enjoy.
I was wondering if it would be a good idea to request an examination and if other people thought it was bad or perhaps irresponsible that I haven't been tested. I was also wondering if anyone could give me advice as to what to expect on a test. Since I haven't technically advanced via evaluation, am I still a rokkyu?
I would ask to be tested, simply because I think testing is a good experience. It's an opportunity to practice your Aikido under scrutiny and under a little bit of pressure, which don't exists in normal training. In my dojo (which is independent), real testing in a "requirements to make the grade" sense doesn't start until the higher kyu ranks at least. For lower grades, testing is seen partially as a way of providing some reference points in the development of your Aikido but also as a part of training (bringing Aikido out under pressure). Gradings are also quite a buzz! You might find you enjoy it.