Working Effectively with Legacy Code

Chapter 8: How Do I Add a Feature?

This has to be the most abstract and problem-domain-specific question in the book. I almost didn’t add it because of that. But the fact is, regardless of our design approach or the particular constraints we face, there are some techniques that we can use to make the job easier.

Let’s talk about context. In legacy code, one of the most important considerations is that we don’t have tests around much of our code. Worse, getting them in place can be difficult. People on many teams are tempted to fall back on the techniques in Chapter 6, I Don’t Have Much Time and I Have to Change It, because of this. We can use the techniques described there (sprouting and wrapping) to add to code without tests, but there are some ...