There are a few things to consider when testing a generics class. First, it's important to make sure that the class is correctly type-safe. This means that it should only accept objects of the correct type, and that it should not allow any type of object to be stored in the same collection. Second, it's important to test that the class correctly implements the interface it claims to implement. For example, if a class claims to be a List, it should support all of the methods defined in the List interface. Finally, it's also important to test the class's behavior under different types of input. This includes testing how it behaves when given null values, invalid values, and edge case values. By testing all of these different aspects of a generics class, you can ensure that it behaves as expected and that it is fully functional.