Test-Driven Development is one of the most controversial development processes. Instead of planning everything ahead, you develop your program incrementally as well as simultaneously and rigorously test it. Kent Beck is one of the most proeminent advocates of this method and this book is the Bible of TDD.
Content and opinions
TDD is about testing while developing, so it is of no wonder that the first part of the book which expose the methodology is done with the help of an example. Small steps, one of the main ideas behind TDD, in the explanations result in a lot of small chapters that explain how to do one thing.
The second part is about the main tol for TDD: xUnit. Its goal is to provide a standard tool for all languages.Well, in fact, it is different implementation, but some are not as easy to use as JUnit, the Java implementation. Some languages are more easy to cope with TDD than others.
The third part is a formal list of patterns to efficiently develop with TDD. What do you need to test something completly? What do you need to go from a test to the actual associated solution? This is the kind of questions the patterns try to answer.
There are a lot chapters with simple ideas in each one. What bothers me is that they could have been hierarchized a little bit more, but really, this is not an issue here. TDD is something that everyone should do, but there are some domains where it is more difficult than in other. For instance, hw would you test a complex stochastic scientific module? This is a question that remains open at the end of the book. For general IT, it answers every question on testing though.