Refactoring

Refactoring is the third step of TDD. After GREEN, assess if refactoring adds value. Refactoring improves the structure of code that already works; it never changes observable behavior.

When to Refactor

• Always assess after green
• Only refactor if it improves the code
• Establish a reversible baseline with a known test result before refactoring
• Pin the behavior the refactor must preserve with a passing test first

Reversible Baseline

A refactor needs a state you can return to, so a broken slice costs one restore instead of a debugging session. A commit is one way to record that state, not a requirement. Refactoring uncommitted code is safe when the baseline is recorded another way.