Review - Pragmagtic Unit Testing in Java with JUnit

Refusing to rest on their laurels from their 1999 success The Pragmatic Programmer, Andrew Hunt and David Thomas are back with a vengeance. They've taken a step back from their previous title to write The Pragmatic Starter Kit, billed as a prequel to The Pragmatic Programmer. The Pragmatic Starter Kit, meant to lay the foundation for a pragmatic programmer, consists of three titles: Pragmatic Version Control, Pragmatic Unit Testing, and Pragmatic Automation. Together, these titles show how to set up a sound development infrastructure, and educate as to fundamental practices, tools, and philosophies which may be used to enhance productivity within this infrastructure.

Pragmatic Unit Testing, the second volume of The Pragmatic Starter Kit, teaches the developer to code smartly by practicing a regime of disciplined unit testing. Hunt and Thomas begin by convincing the reader just why it is we must write unit tests, and then quickly debunk the most common excuses developers use for not testing. Now that we are suitably convinced, the authors go on to explain how to plan and write unit tests, how to work with the JUnit framework, and how to use mock objects.

Most books on this subject don't really go too far beyond how to write unit tests. Where this book stands head and shoulders above the rest though, is the great depth the book goes into showing us exactly what tests need to be written. Through a series of helpful mnemonics, the reader is taught exactly what to test, how to correctly test boundary conditions, and what the properties of good tests are. We are also given general testing principles to keep in mind, as well as questions to ask ourselves about our code while testing. The concepts given herein are invaluable, and if the book ended with just this, it would be well worth the money.

The book doesn't stop there however. The authors offer excellent advice for integrating unit testing within the scope of a project in a team environment, and we are given a look at how unit testing can influence design. Exercises are presented to help the reader practice key concepts throughout the book.

There are a couple of things that this book isn't. This book is not a treatise on how to unit test specific components in an application. As stated previously, this book is less about how to test specific components, and more about what tests should be written in the first place. This book also does not overtly espouse any particular process. Extreme programming and test-driven development are certainly mentioned, but they are not championed above other processes.