Programmer Musings

Review of Perl Testing: A Developer's Notebook

Perl Testing: A Developer's Notebook
Ian Langworth and chromatic
O'Reilly, 2005

This is the first book I have read from the new O'Reilly Developer's Notebook series. Although the style of these books probably won't work for every topic, it works particularly well for a book on testing. Each chapter is organized as a set of labs. These labs walk through some portion of the topic with the goal of developing practical skills.

Each lab revolves around a task. They don't delve into theory, they focus on describing how you perform the task. Unlike O'Reilly's Cookbook series, this is a directed set of tasks. Much like labs in a class, the labs in this book start with basic testing skills and work to build more advanced testing skills. The goal of this set of labs is to help you become proficient in the skills needed for doing quality unit testing of Perl code.

I have been doing testing with the Perl programming language for some years now, so the first few labs were review. But, the labs swiftly escalated to more advanced topics that I was either light on or had not explored at all. In addition to labs about Test::Simple, Test::More, and Test::Harness, the book covers:

• testing the POD documentation in your modules
• coverage testing
• testing exceptions generated by code
• testing warning generated by code
• building testing libraries to simplify testing
• mocking objects
• overriding system calls
• testing databases
• testing websites

and many more topics related to testing. This little book is packed with practical information and labs that help you improve the skills you need to build quality testing for your Perl code.

I really don't expect this book to become a well-worn reference book that stays near my desk at all times. However, I don't expect to let it get far away. Since few of us need to use all of our testing skills on every project, some skills become rusty over time. Anytime I find some of my testing skills have gotten rusty, I expect to grab this book and run through the appropriate labs to sharpen the skills I need.

If you want to know why you should be unit testing your Perl code, there are many books out there that will explain. If you are looking for an explanation of Test Driven Development, this is not the book to read. Once you have decided that testing is important to you and your projects, this is the book you need. I would not say that there are no other resources for learning this material, but this may be the fastest way to build the appropriate skills that I've seen.

It also helps that the authors have a very relaxed style that helps you feel more like they are working along side you than lecturing at you. The titles of the sections are very casual (How do I do that?, What just happened?, etc.) This makes it easy to read the next part and get back to working on the meat of the lab.

I would recommend this book to anyone writing Perl code. We all need to be doing testing to improve our code and our designs. The key difference between good testing and bad testing is the skills to make every test count. This book teaches those skills.