Throughout the previous chapters, you received an impression of how architectural fine-tuning goes hand in hand with the test first approach. You've experienced that a safety net of well-written tests prevents collateral damage on changes even if more substantial alterations due to the lessons learned in the course of system development should be necessary.

As a consequence, justified changes are less risky to achieve and, chances are, they get incorporated properly and consistently. This, in turn, promotes a healthy structure, freed of dull workarounds that bite back at any given opportunity. Obviously, software implemented that way is easier to maintain and faster to evolve. Overall, it improves the odds...