Test Driven Development: By Example

I enjoyed reading this book, however I must advise that non-coders will probably have difficulty in staying with it. I don't mean that as a put-down of any kind. It's obvious that the intended audience is the developer who is trying to understand the concept of test-driven development. A tester, however, would learn in this book that test-driven development uses tests that are different in nature and rigor than those commonly thought of as "unit tests." I think Beck does a good job in explaining test-driven development in a way that is easy to understand. I still have some concerns about the nature of test-driven development, such as the emphasis on function over design. But I think Beck achieved a reasonable goal of presenting by example what test-driven development is all about. The goal of test-driven development is a reasonable way to achieve "clean code that works - now." As a tester, I think the awareness of test-driven development is a good thing. I also think that this technique must be combined with other methods, such as getting quality requirements, verification and validation, to achieve a final result that meets the users' needs.Readability - 4Coverage of topics - 5Depth of coverage - 5Credibility - 5Accuracy - 5Relevance to software quality - 5Overall - 5

This book has nothing in it that you don't know you should be doing. You know you should test your code. You know that you should make sure changes don't break things. I'll bet that you haven't actually taken the steps to make sure that you do this though. Kent walks you through a good way to develop code: write the test code as you write the actual code. I've actually put this into practice and it's surprisingly easy to follow the recommendations. As you write a new function, write some code that calls it in a few different ways. When it comes time to give your code to someone else (check in to source control, deliver to customer, use on a bigger project), you have a fair sense that things will work. Again, you already know that you should test things. This book presents one really great way to do that. It's worth taking a few hours and reading this one. Buy it so that you can re-read it once every year.

Let me say first off that I agree with much that Kent Beck has to say: 1. Testing should be done along with the coding. 2. Use regression tests to be confident of making changes. 3. In many ways testing can be used as documentation since it is much more definitive than specification documents. 4. Testing should be used to have the client sign off on a product. In reading the book I learned the specifics of how tests are designed in TDD. It seems reasonable and I am going to make a conscious effort at designing my tests in the way suggested.Where I disagree is in the use of the tests to drive software design. In the first part of the book, which I think is the most important part, a very good coding problem is analyzed - it is realistic, limited in scope and far from trivial. I followed along until I reached a point where things stopped making sense. I skipped ahead to see where things were headed and then things became clear.What is being advocated is a type of bottom up design approach. This may work for some. It may even be that the book faithfully reproduced Beck's reasoning process. It does not work for me. I first have to see the larger picture, what he refers to as the "metaphor." The whole thing would have been much clearer to me if at the beginning I was told that one approach to summing money in different currencies would be to use an array to store the information but that instead the implementation would create a list similar to how things are done in LISP.I urge the reader to judge for him/herself. Like I said this is a good example to go through. I even learned some things about more advanced uses of object oriented programming. As for software design I am going to stick with dataflow diagrams. They are still the best tool that I know of for putting together software, UML notwithstanding.

The are a small number of writers who can teach programming skills effectively. Kent Beck is one of them. There are a small set of practices that you can adopt on your own that will have an clearly observable impact on the quality of your results and the quality of your work day. Test Driven Develoment (TDD) is one of them. If you are a software developer, you want to buy, read and study this book.TDD fits development into a three micro-phase cycle: create a test that embodies your requirement, write code that passes the test, make the code run clean. Each phase has different goals, patterns and pitfalls. Like any good coach, Beck walks you through these in detail. He uses multiple examples: most notably a business model in Java and a unit testing framework in Phython. He follows up with a question and answer section that reviews common patterns in test driven development cycle. The level of learning involved in doing TDD is profound. The best way to read the book is to do the book. Skills come from doing not reading. I did the examples (in another language) and it made all the difference in what I learned.A footnote for managers: TDD is the opening wedge for a set of practices known as extreme programming (XP) or agile development. Test driven development is powerful enough to work on its own for the single delevoper. If you want to realize its full value, however, you need to embrace the full set of XP practices for the whole organization.

It's about time that someone wrote this book. Some programmers have been doing test-driven-development since the earliest days of our profession, and the rest of us have been wondering why it is so hard to development software the "traditional" (non-TDD) way.Test-driven development (or as I prefer to call it, test-driven-design) helps you figure out the most useful interface to your class-under-test, without getting you into the psychological trap of not "really" wanting to test (and thus prove faulty) your "wonderful" code, because your code doesn't exist yet. The tests help you think about the implementation in small, mostly painless, steps.TDD also helps you write portable code. By getting portions of the logical parts of your application done first (the "model" of "model-view-controller"), you easily keep the logic code OUT of the GUI code. Typically, programming without test-driven-design makes it too easy to put all your logic into your GUI class. Almost all books on how to use MFC and other GUI class frameworks mix the logic code with view code -- you should read this book so you can be a better programmer.