Working Effectively with Legacy Code

Chapter 9: I Can’t Get This Class into a Test Harness

This is the hard one. If it were always easy to instantiate a class in a test harness, this book would be a lot shorter. Unfortunately, it’s often hard to do.

Here are the four most common problems we encounter:

1. Objects of the class can’t be created easily.

2. The test harness won’t easily build with the class in it.

3. The constructor we need to use has bad side effects.

4. Significant work happens in the constructor, and we need to sense it.

In this chapter, we go through a series of examples that highlight these problems in different languages. There is more than one way to tackle each of these problems. However, reading through these examples is a great way of becoming familiar with ...