The Japanese Language Proficiency Test is the most well-known test of Japanese proficiency for non-native speakers. There are five test levels (N5, the lowest, to N1, the highest). Once students have a basic understanding of Japanese, it can be very rewarding for them to take a test like this to prove their level of proficiency.
Kanji are inherently interesting and the Kanji Proficiency Test is a good way to motivate students to learn the characters. This test is designed for native speakers of Japanese, but the workbooks can be used to teach non-native speakers. Link: Books on Amazon.co.jp