How are the ranks tested and what do they mean?
For now, this answer is restricted to kendo as adjudicated by the Canadian Kendo Federation. Iaido has different test requirements but the comments on experience and ability are still fair. Different countries have differing examination requirements but they are roughly similar. For kendo, the rank test consists of 3 parts: kata (two-person forms), kiri-kaeshi (diagonal cutting exercise) and ji-geiko (free sparring). For ranks below ikkyu, the kata is dropped. Kids below ikkyu do kakari-geiko (controlled attacking practice) instead of ji-geiko.
