The Rails testing landscape has blossomed far beyond Test Unit, and this book does a good job of describing the current alternatives, giving some background, pros, cons, and how to set up and use each one. Given the frequency with which many developers hop around, this book will prove invaluable in getting you up to speed quickly on whatever tools are being used in your new environment. It will also enable you to make informed decisions to use (or not use) something if you are starting from scratch.

As a final bonus, tech books are notorious sleep-inducers, but Noel has an excellent dry sense of humour that serves to turn this book into a smile-inducer instead.

We are finally realizing how important testing is, which makes this book a must-have for your coding toolbox (and career).

This is a great book if you're looking to understand:

(A) the various tools that can be used to test all the various parts of a Rails app

(B) how and when to use those tools.

This is a good overview of the "State of the Art", as of publication date, of the various testing technologies for Rails apps. It has good sections on the basic tools that come with Rails (the standard unit testing package and fixtures) including the often overlooked integration tests. Then it's on to the tools which don't come standard; Shoulda, RSpec, and Cucumber. The book does a good job of showing how to use these tools, and gives a thumbnail sketch of their philosophies, so you understand why they were built. The sections on the javascript and view testing tools Jasmine, WebRat and Capybara ("the rodents") are useful pointers towards what can be done with these tools, but it doesn't cover them in the same depth as some of the other tools.

I've found it to be a good tutorial, and a pretty good reference ("How do I set up an RSpec controller test again?"). Highly recommended.