This code repository is the companion to my book on Marionette.js testing.
Even if you don't have the book, you can learn a lot from looking through the commit history. But if you're serious about improving your app's maintainability, I suggest you consider purchasing the book: typical mistakes and various tips and techniques are indicated in the book and absent from this repository.
If you're interested, you can view a sample of the book at http://samples.leanpub.com/marionette-testing-sample.pdf