Unit testing, done right, can mean the diff erence between a failed project and a successful one, between a maintainable code base and a code base that no one dares touch, and between getting home at 2 AM or getting home in time for dinner, even before a release deadline.
The Art of Unit Testing builds on top of what's already been written about this important topic. It guides you step by step from simple tests to tests that are maintainable, readable, and trustworthy. It covers advanced subjects like mocks, stubs, and frameworks such as Typemock Isolator and Rhino Mocks. And you'll learn about advanced test patterns and organization, working with legacy code and even untestable code. The book discusses tools you need when testing databases and other technologies. It's written for .NET developers but others will also benefit from this book.
Something for every levelMarch 14, 2010 wiredweird(Earth, or somewhere nearby) Osherove covers new ground in this brief, dense book: unit testing. Although unit testing has become something of an article of faith among the Xtremists and in many industrial settings, the only way to learn it has been under the guidance of an experienced tester. (I recently had a shocking experience with an undergraduate class. Apparently, testing had never come up in their four years, and some didn't even know that a test should distinguish correct from incorrect behavior.) This isn't really a formal program of study, but it's the best how-to I've seen to date.
The author covers the topic at many levels. For the beginner, he presents the fundamentals like what a unit test is and even why unit testing is a good thing - which, believe it or not, some people still argue against. He shows how unit testing interacts with other parts of the design cycle, such as refactoring. Among other things, testing a module in isolation requires that the code be isolated, that its dependencies be clearly identified and be amenable to replacement by test fixtures. I didn't see Osherove state this outright, but one benefit of the unit test lifestyle is that test-friendly code has fewer dependencies and more explicit ones - something that makes maintenance enormously easier, or even possible in some cases.
Large parts of this book refer to specifics of the .NET environment or of specific tools, of which dozens seem to exist. Even if you don't use those tools or that environment, there are still important lessons in these sections, since concepts are often transferable even if particulars aren't. He adds new meaning to common knowledge, too. For example, he defends some cases of redundant tests written by different people, on the grounds that they're likely to test different things. This puts new words to the "N-version programming" concept familiar in the fault-tolerance world. There, the hope is that different implementations will contain different defects; here, the observation is that different implementations often detect different defects.
Of course, I found a few things to disagree with. Osherove makes little mention of randomized testing, something that I often find useful - directed tests cover the cases I was thinking about, but randomized testing often reveals cases I wasn't thinking about. And, although I generally agree with his premise that tests themselves shouldn't contribute to the debug burden, I find that looping over data elements that specify test cases can decrease global test complexity at some cost in local complexity.
Beginners shouldn't expect to understand everything that Osherove presents. Likewise, experienced testers should be patient with the introductory material that leads up to the advanced discussion. All of this book will have value to one reader or another, but any one reader might not find all of it useful. Also, unit test tools are still maturing, so discussing the many tools available makes parts of this book seem scattered. Still, if you don't have a test guru to study with (or even if you do), I strongly recommend this book.
-- wiredweird
Great introduction to unit testingMarch 12, 2010 Nelson H. Ferrari(Alpharetta, GA United States) I bought this book because I had to start writing some serious unit tests and I didn't have a good idea of what to do.
Of course, if you are at the point you have to write unit tests, you have a job programming, so this book is certainly not for beginners (at least not in computing). The examples are in C# but the language is not very important for this book
He uses a different set of programs as the base of his examples, but this doesn't matter much, because the techniques he presents are very useful. The very first unit test I wrote after reading only a couple of chapters was way better, and easier to write and understand than the one I wrote just before it. And the one after I finished the book was even better.
As he mentions somewhere in the book, any type of testing is viewed as a waste of time, but the quality of the code improves a lot. He presents not only how and why to start writing unit tests but how to convince your company how to do it.
The book paid for itself a couple of times already, even though I only had it for about a month.
Must read for NUnit TestingFebruary 11, 2010 Steven Koh(Singapore) 0 out of 1 found this review helpful
This is a good book for the intermediate developer.
For beginner to NUnit, I would recommend the Pragmatic Series.
Great book to start unit testing and improve your styleFebruary 5, 2010 Alan Mendelevic(Vilnius, Lithuania) This is a great book for unit testing beginners and those who want to write better unit tests. There are a couple drawbacks mostly related to formatting/presentation but the content is top quality. Highly recommended.
The ultimate book on unit testing.February 4, 2010 Alvin Ashcraft(West Grove, PA) As a developer who started working in Visual Basic 15 years ago and only began to explore unit testing and Test-Driven Development (TDD) in the last four to five years, I was blown away by The Art of Unit Testing. I wish this book had been written many years earlier. The code samples in the book are written in C# and the tools referenced target .NET, but the concepts apply to any language or platform.
