Just a couple of parting thoughts. Firstly, my comment about not being able to run tests that declared their own variables under a combinator template isn't quite right. You can just edit the combinator template to wrap each test case in braces so that it runs in its own independent block. Secondly, in case it's not obvious, you can use the "Extra template data" field of each test case in various creative ways, e.g. to add extra testing code that's hidden from the students to avoid confusing them.