You might want to look at http://www.venusjs.org/ to get some ideas for supporting multiple testing frameworks. It uses an annotation approach kind of how you include files for tests. The automatic mocking is pretty awesome though.
Not trying to be tangental, but I believe this is true with EmberJS which was originally modeled off of Coaco. You inherit from Ember's base Objects (ArrayController, ObjectController, etc) and rarely find yourself extend classes that you write. Here is a hierarchy of the "base" classes. http://emberjs.jsbin.com/bahetoka/1
There are plans to have a "cookbook" section on the EmberJS site that will be one of the go to places to answer the question of "How do I do X in Ember?". It's currently on the master branch for the site, so expect that soon. In the mean time here are some other video resources http://www.embercasts.com/ and http://ember101.com/. They may be slightly out of date but they are still relevant. Make sure to look in the console for warnings about deprecations.