Prepare

Our code will be written test-first, automatically making our code testable. That in turn means our code will be more modular, and therefore more maintainable and more extendable.

Change

As requirements change and insight grows, we find out that the current design is sub-optimal. Refactoring is the toolkit to improve our design. We are confident to refactor, because we have our test suite.

Evolutionary!

All of this is easier with a small feature, a small test, and a small refactoring. As the Dutch say: "Vele kleine maken een grote"; many small ones yield a big one. This holds true for features, test suites, and refactorings.