Refactor With a Safety Net
Plans a refactor as a sequence of individually safe, individually shippable steps, with the characterisation tests that make each one verifiable.
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Running it, start to finish
- Paste the code, the real problem with it and your current coverage.
- Write the characterisation tests before changing a line.
- Ship each step on its own, and stop at a stop point if you run out of time.
What you get back
The output this produces, every time.
- Tells you when not to refactor, which is often the right answer for stable code nobody touches.
- Captures current behaviour — bugs included — before anything changes.
- Sequences the work so it can be interrupted at several points and still leave the code better.
Getting better results
Where this usually goes wrong, and how to avoid it.
- Be honest about existing tests. If coverage is thin, section 2 becomes most of the work, and that is the correct answer rather than a reason to skip it.
- Ship each step separately. The plan's safety comes entirely from that. Batching six steps into one pull request discards the property that made them safe.
- Decide the arguable bugs upfront. Section 2 flags behaviour that looks wrong. Deciding mid-refactor whether to preserve it is how a behaviour-preserving change stops being one.
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Written for The AI University. Every prompt in this library is original work — authored, tested and revised here, not collected from elsewhere. 365 of them, free with an account.