That's an advantage in my book... it is testing the unit (function in this case) and it is testing all the corner cases... do you have a name for each of them? Description through comments is much more suitable IMHO.
I really hate some things about the Rspec/Cucumber suite, but providing a way to output what the tests are testing as they run is a major advantage. I like being able to run my test suite and see "it does what it's supposed to do in this case" output.
At a glance, the Pyret default appears to be that tests run silently. How do I know the right tests were run?
Corner cases? Tests test the behaviour of the function. Functions, depending on their complexity, have a range of behaviour. And yes, you should (usually) be able to come up with a name for it. As a bonus, you'll get immediately an idea of what broke upon test failure.
