How do I use AI to refactor legacy code safely?
Feed the AI your existing tests first, then the code to refactor. Ask it to preserve all test-passing behavior while improving structure. This anchors the refactoring to verified behavior rather than assumptions.
When to use this
When improving codebases with good test coverage that you want to modernize without breaking.
When to skip this
For code without tests—write tests first, or the AI may change behavior unintentionally.
Advanced AI coding assistant, existing test suite