You’ve already heard this, but it can’t be stressed enough:
Increase unit-test coverage to boost your confidence in continually improving your design.
In this chapter we focused on improving our design based on a couple of big design ideas: the SRP and command-query separation. You owe it to yourself to know as much as possible about these and other big concepts in design. You also owe it to yourself to understand the “little” concepts in design and how small code refactorings can make a big difference. Armed with a stockpile of design smarts, your unit tests will allow you to refactor your code to a place where it more readily supports ...