Ideally, we would run insulated, fast, and consistent tests on all parts of a Backbone.js application without any modifications. In actuality, these goals encounter hurdles for at least some of the real code paths in a Backbone.js application.
We want to test Backbone.js components in isolation, but many components have dependencies on other parts of the application. We also want the tests to run quickly, but many parts of a Backbone.js application can slow things down, including the following:
Network communication, such as persisting a model state to a remote backend datastore or a third party API
Complex DOM manipulation with Backbone.js views and templates
Timed events and DOM animations, especially those that deliberately wait (such as a slow jQuery fade)
Finally, many events and execution paths in a Backbone.js application are non-deterministic. For example, parallel network requests and user inputs can be received by the application in any order. To deal with these...