You will find a lot of tutorials online. I am listing a few of them; these are highly recommended and widely followed by developers:
Developing Backbone.js Applications by Addy Osmani (http://addyosmani.github.io/backbone-fundamentals/)
Blog posts by Derick Bailey (http://lostechies.com/derickbailey/)
Patterns For Large-Scale JavaScript Application Architecture by Addy Osmani:
Scalable JavaScript Application Architecture by Nicholas Zakas (http://www.youtube.com/watch?v=vXjVFPosQHw)
If you are a beginner, you may find the Backbone tutorials pretty helpful to understand the initial concepts (http://backbonetutorials.com)
The QUnit and SinonJS documentation provides complete details on test frameworks. The following are a few books and tutorials that you may find handy to help you master these frameworks:
Unit Testing Backbone.js Apps with QUnit and SinonJS by Addy Osmani (http://addyosmani.com/blog/unit-testing-backbone-js-apps-with-qunit-and-sinonjs/)
QUnit Cookbook by the jQuery Foundation (http://qunitjs.com/cookbook/)
SinonJS by Christian Johansen (http://cjohansen.no/talks/2011/xp-meetup/#1)
Unit Test like a Secret Agent with Sinon.js by Elijah Manor by Elijah Manor (http://www.elijahmanor.com/unit-test-like-a-secret-agent-with-sinon-js/)
Apart from the previously mentioned resources, the Backbone.js wiki provides an updated list of the important plugins and tutorials, some of which are as follows:
Backbone plugins and extensions at https://github.com/jashkenas/backbone/wiki/Extensions,-Plugins,-Resources.
Tutorials, blog posts, and example sites at https://github.com/jashkenas/backbone/wiki/Tutorials,-blog-posts-and-example-sites.
A number of Backbone.js plugins listed by popularity at http://backplug.io/.
Backbone-Debugger at https://github.com/Maluen/Backbone-Debugger. This is a Chrome browser extension and can be helpful while working with Backbone applications. A similar Firebug extension can also be found at https://github.com/dhruvaray/spa-eye.