Refactoring: Improving the Design of Existing Code

Chapter 4Building Tests

Refactoring is a valuable tool, but it can’t come alone. To do refactoring properly, I need a solid suite of tests to spot my inevitable mistakes. Even with automated refactoring tools, many of my refactorings will still need checking via a test suite.

I don’t find this to be a disadvantage. Even without refactoring, writing good tests increases my effectiveness as a programmer. This was a surprise for me and is counterintuitive for most programmers—so it’s worth explaining why.

The Value of Self-Testing Code

If you look at how most programmers spend their time, you’ll find that writing code is actually quite a small fraction. Some time is spent figuring out what ought to be going on, some time is spent designing, but ...