Refactoring is not intended to be a special, high-ceremony, once-in-a-while activity, like plowing under the whole garden in order to replant. Instead, refactoring is a day-to-day activity, taking low-risk small steps, more like weeding and raking. Instead of a free-for-all, wholesale rewrite of the codebase, it’s a targeted, precision approach to help keep the code easy to change. In order to guarantee that the external behavior hasn’t changed, you need good, automated unit testing that validates the behavior of the code.
