Jasmine follows the same spec/BDD style as RSpec for Ruby and Kiwi for Objective-C (Kiwi is very good BTW). That is, set up your context using ‘describe’ + ‘before’, then make assertions on the post context state using ‘it/should’ blocks. Jasmine runs your test suite in the browser and seems to be blindingly fast.
For me, Jasmine tests also highlight one of the reasons I like Coffeescript more than plain old JS – less lines of code. BDD specs tend to have a lot of nesting as you build up contexts, so Jasmine written in JS tend to have a lot of nested functions. As these test functions tend to be pretty straightforward assertions, it’s seems a reasonably fair to compare coffeescript vs the generated js. Here’s one of my tests, notice that the coffeescript version is just 49 lines and pretty easy to read; the JS version is 78 lines and to my eye it’s not terrible but it is harder to read.