Legacy Refactor Protocol

This skill guides the safe refactoring of "legacy" code (code without tests or difficult to understand code).

The Algorithm

1. •Identify Seams: A place where you can alter behavior without editing the place in question (e.g., via subclassing, interface extraction).
2. •Characterization Tests: Before changing ANY code, write tests that capture the current behavior (bugs and all).
   • •Goal: Ensure you don't change behavior unintentionally.
3. •Break Dependencies: Use dependency injection to isolate the code module.
4. •Refactor: Make your changes (clean code, upgrade lib, etc.).
5. •Verify: Run characterization tests.

Strategies

• •Sprout Method: Write new logic in a new method and call it from the old one.
• •Wrap Method: Rename the old method, create a new method with the old name that calls the new logic + the old method.