First, you never have to test.
If you want to test, you have to be a member of the United States Aikido Federation (USAF), which costs $35 a year. This money does not go to Aikido of Norfolk.
We do all Kyu (below black belt) testing in our dojo. There are six Kyu ranks. Almost all the dojos in our federation (USAF) wear white belts for all the kyu ranks; a few may use color belts. At seminars where people from many dojos come together, all kyu ranks should wear white belts. The test fee, which goes to the USAF, is also $35, per test. You get a certificate and a booklet where you can keep track of your promotions and the seminars you attend.
Black Belt or Dan testing is held at various seminars which are taught by a Shihan (highest teaching rank). The fee, which goes to Japan, is around $200, depending on the current value of the yen.
Here is a set list of requirements for each rank, showing what techniques you have to know, and how much time has to pass between each test before you can test again.