Writing test cases is not the same as writing them for other code languages. Although based on Java, Adobe Experience Manager is really kind of its own beast. This can make it difficult to figure out how to write your own test cases, especially if you are just starting out as a new AEM dev. Yogesh Upadhyay of wemblog.com put together some great examples of how to write test cases for AEM. He put a lot of work into this and it should help you out tremendously.