You test more than you think. There are two types of programmers:
1) Ones that make deliberate tests for their code
2) Ones that run their code at random intervals to see if it “works”
In both cases you are testing your code. In the first case your code is better understood, well documented and highly robust. In the second case, you cross your fingers and hope that your code wont drag you back into debugging hell.
This book is a valuable introduction to testing techniques. I have applied the testing principles of this book to write very robust code which saved the company I worked at months of potential debugging. Sure, the overhead of writing test ready code took a week or two. But I sat back and watched the team leader spend several weeks wasting time debugging his untested code at the integration phase.
I have read a few software testing books. Among them, this one is the most concise, applicable and enjoyable book on testing. It covers why engineers are repelled by testing and what you can do about it. In 150 pages you will learn everything you need to know to write intelligent and effective tests for your software.
Take control of the quality of your software. Life is too short for debugging.