I'm not Kent Beck so I expect you to be a little hesitant about the book. Good, you should never believe what marketing is telling you! :) Here you have a chance to learn from other readers whether the book is worth your money and time.
Despite the Java/TestNG/Mockito orientation that the title might suggest, the book contains a high percentage of general unit testing knowledge that can be applied (mostly) independently of the language and tools that you are using.
This book is highly recommendable to all software developers interested in unit testing, particularly if you are working in a Java context.
This is one of the last chapters which explains how to make unit tests manageable, so they do not become a burden as the project develops and changes are introduced.
P.S. Hint: use "fullscreen" option. :)

My name is
Tomek Kaczanowski, and I’m happy to present to you the results of all my hard work over the last year and a half. This book has been written on the basis of my experience as a senior Java developer, trainer, mentor, technical team leader and merciless code reviewer. :)
The book has been proofread by several TDD, TestNG and Mockito experts, and corrected by a native speaker, so I feel pretty confident about recommending it. Okay then, let’s forget about modesty: I reckon this really is the best book dealing with unit tests on the market! I hope you’ll share my opinion when you’ve read it! :)
Personally, I would have been really happy to have had the chance to read a book like this some time ago: it would have spared me several grey hairs, for sure! :) I would also be happy if my colleagues were to read it and follow the advice they found there... :)
I'm self-publishing the book so if you could spread the word, that would be really nice! Every little twitt counts, you know. :)