Come along as we test the "Contact Manager" application (developed in Backbone.Marionette.js: A Gentle Introduction) and refactor the messier parts. You'll learn the fundamental concepts and apply them through guided exercises, using Sinon, Mocha, and Chai.

By the time you're through with the book, you'll understand how and why to keep tests independent, as well as avoiding duplication in test code with judicious refactoring and helper functions. These skills will assist you in improving the application code and developing new features without introducing regressions. We will also cover how to run tests from the command line, so your new test suite can be used within a continuous integration environment.

We'll cover testing the application code in such a way that you will rapidly be able to apply these concepts to your own projects. We will see how to:

• set up and tear down test environments;
• handle tests for asynchronous functionality;
• test code relying on timers;
• write readable assertions and test code;
• leverage javascript to keep test code short, DRY, and readable;
• use spies and stubs to keep tests decoupled from application code specifics.

And more, of course. The entire book is platform-/framework-independent as is doesn't rely on any server: we'll be testing only the client-side code.

Do note, however, that we implement the verifications using mainly stubs (with occasional spies), and mocks are only discussed in the last chapter. Didn't understand that last sentence? Don't worry: you probably won't care about the difference. This book will show you how easy testing can be, and will do so painlessly!