Quality Code: Software Testing Principles, Practices, and Patterns

Unit Testing for Coverage

Code coverage tools provide wonderful assistance in writing, crafting, and maintaining your tests. They graphically show you which code you executed in your tests, letting you know if you hit the code you intended and which code you have not hit yet.

Code coverage by no means gives you an exhaustive understanding of how you have exercised your code. Many constructs branch to multiple code paths in ways that cannot be statically determined. Some of the most powerful features of our various languages—the features that give us the most useful abstractions—work in ways that are transparent to static analysis. While the coverage tool may show you what has been executed when you use these mechanisms, it has no way to know ...