Test-driven development (TDD) is one of the hot topics in the recent "agile revolution". Unfortunately, there aren't too many texts currently available that take an in-depth look at the subject. David Astels jumps into the fray with his new book, "Test-Driven Development: A Practical Guide", in order to help fill that void. Giving a nod to Kent Beck's "Test Driven Development By Example", Astels views his work as a complement to Beck's, focusing on the practical techniques and tools necessary to best make use of TDD.
The book first touches on some topics fundamental to TDD, such as refactoring, programming by intention, and of course the basic theory behind TDD. Appendices further flesh out this material by addressing extreme programming and agile modeling.
Although other members of the xUnit family are looked at, this book is squarely focused on JUnit and Java. As such, the text goes into detail about using JUnit, including the API, and how to go about the task of writing tests. Along with the JUnit coverage, the reader is presented with information on several JUnit extensions and JUnit related tools designed to aid the TDD process. Where this book really shines is in its coverage of mock objects and techniques for testing GUIs within JUnit.
The meat of this book rests in a very detailed walkthrough of a project using TDD. Astels leads the reader through every test and every refactoring along the way, from inception to the finished product. This is probably the next best thing to sitting down for a pair-programming session with a TDD guru.
Unfortunately, there are a couple of complaints I feel the need to point out. The project presented is a Swing application that persists its data in a flat file. There is no coverage provided for testing web based enterprise applications. While mention is made of DatabaseChecker, a test utility suitable for simple database tests, Astels chose not to have the example project use a database for persistence. As a consequence of this decision, this common task is left unaddressed.
Despite these omissions, there is still much to be gained from this book. I feel a reader may obtain the most benefit by downloading the sample code and working through the example project step-by-step along with the text. If you are interested in a practical guide to TDD, this book is definitely worth a look.