For those who are not aware of what an aptitude test is, it is basically a test that determines where you're strengths are and where you would work best in the pack. I was thinking that every time we get a new member once they've been officially accepted to the pack and chose their clan they would be tested to see what rank suits them best (if a large group of members joins around the same time they will all be tested all at once). They would be tested most likely by a member of high standing and be supplied with questions and scenarios that the wolf would have to answer honestly. According to their results it would help them discover which rank best suits their wolf, though they can choose any rank they wish.

The tests would most likely be sent out through PM and there could be like a mini event in the rp, it would work as an official welcoming to the pack. The wolf/wolves taking the test would also be faced with several quests/missions or whatever that they would have to complete to be fully accepted in their rank. So, after a wolf took the aptitude test they would be set with several different missions (ranging from maybe three to four) that they must complete successfully to join their wanted rank, if they fail they may either choose to try again (there could be maybe 3 chances) or pick a new rank to apply for. Maybe after they are accepted into their new rank they could have a week or two of training in that rank, tried by a devoted member of that rank.
I tried to explain best I could, if there are any questions just ask here c:

Mhm, basically c: