There are a few different ways that you can tell what courses have quizzes and tests available. The quickest way is to go here: www.digitaltutors.com/11/training.php?cid=369
If you want to know which courses have quizzes and tests as you are browsing the training library, look for the quiz or test icons on the appropriate pages. For example, quizzes are always on lessons whereas tests are always for full courses.
Another way that you can tell if a test is available for a course is to go to the "My Courses" page in the My Account section. If there is a test available for a course that you have watched, you will have the ability to start the test directly from that listing.