Continuous coverage

You've learned how to use a couple of different testing tools in this chapter, but what about when to use these tools?

When it comes to code testing, there's a metric known as "code coverage" that tells us the percentage of our code that is covered by tests. The first thought of a passionate architect starting a new project is that everything should be covered with tests, tests everywhere!

Realistically, there are things that we just don't need to test; as always, we should take a pragmatic approach. Configuration of components probably doesn't need to be tested; we don't need to test the return values from third-party code libraries; there are many examples.

Having said that, code coverage is a useful way to make sure that a certain level of testing is maintained in a project. For example, we might wish to have 90 percent test coverage of our model code and only 50 percent coverage on our controllers, which contain more boilerplate that...