Beyond Legacy Code

Be Complete

There is an assumption that a suite of tests tells the whole story and is a complete specification. If you don’t specify a test for a behavior, that behavior is assumed to be false. Anything that’s not part of a test suite is assumed not to exist. So you have to have a complete set of tests to cover all the behavior in your system. If you’re really practicing test-first development, you’ll have that complete set of tests. Always write a test to create behavior.

And because you’re creating testable code as you’re writing it, you’ll see a dramatic positive increase in the overall quality of the finished product. There’s a tight correlation between testability and code quality, but please don’t put on your QA hat.

It’s very enticing ...