Friday, 11 April 2008

Book Review: JUnit Recipes by J. B. Rainsberger, Scott Stirling

' "Stop Debugging. Write a test instead" and here's how'. That seems to sum up the book. Wether you use TDD or not, JUnit Recipes helps you get more out of JUnit - perhaps it will help you stave off a move to TestNG?
Contents include 130+ 'solutions' for common tasks. If you check out the contents page then you can see what the authors cover.

People often want assurance from 'authorities' that they are doing the right thing so the book has discussions about 'how much' testing to do and 'how low' to go. 
So guidelines include:
  • "don't test it if it is too simple to break",
  • "don't test the platform"
  • "try the different techniques out and see which you prefer"
  • "test anything in which you do not already have confidence"
Hence guidelines rather than prescriptive practices. The book heavily encourages the reader to try it out and see how it works for you, and provides some alternative approaches.
You do have to work through some of the examples to understand them (or at least I did) and since it acts as a recipe book, you mainly consult it when you need to.
Unlike many cookbooks, Junit Recipes seems to move through in a logical order building on previous recipes so although it doesn't sell itself as a tutorial book you can work through it in that way.
At least you can probably read up to Chapter 6 sequentially, but thereafter the book worked best for me as a dip in and out when required recipe book (presumably the intended usage).
Many tidbits based on experience, of which I have only selected 4 that stood out for me on initial reading:
  • testing floating point values with tolerence levels
  • abstract test cases -
  • have JUnit automatically build test suites "return new TestSuite(MyNewTest.class);" (and other ways of automatically building suites)
  • suite or higher level setups rather than just at testCase level
I didn't know JUnit supported so many ways to build test suites. I found the discussions in Chapter 3 and 4 on how to organise your tests very useful.
Chapter 4 contains a discussion of data driven tests, a technique common to 'system testing' but I don't see used very often at the unit level and looking at the code provided I can see why - I had to go through this several times to get a handle on it and would still want the book in front of me if I tried to do it live. Coverage of the use of test data then increases in Chapter 5.
At Chapter 14 you can start reading sequentially again. So for a first read I would recommend 1-6. 14 -> to the end.
If you use JUnit as your test tool and if you do any of the 'things' covered in the contents list of recipes then I recommend getting hold of this book.
Useful links that have examples of usage in the book:
Related Links:

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