Refactor

Refactor code by making small, incremental changes that preserve behavior while improving structure. Run your full test suite before and after each change to ensure tests stay green, then commit each working state. This approach eliminates duplication, renames for clarity, extracts methods, and simplifies conditionals without altering external APIs.

Apply incremental refactoring guided by TDD principles: verify tests pass, apply a single well-scoped improvement (eliminate duplication, rename variables, extract methods, simplify conditionals, or move responsibilities), run tests again, and commit. This preserves existing behavior while making code clearer and easier to maintain.

Yes. Refactor large classes and long methods incrementally by extracting smaller methods, moving responsibilities, and renaming for clarity. Keep your test suite green throughout by running tests before and after each change, ensuring external behavior never changes while improving internal design.

Running tests before refactoring establishes a green baseline so you can detect regressions immediately. This test-driven guardrail prevents accidental behavior changes during incremental transformations and confirms that external APIs remain unchanged after each step.

Identify duplicated logic, extract it into reusable methods or functions, and update all call sites to use the extracted code. Run tests after each extraction to verify behavior is preserved, then commit. This reduces maintenance burden while keeping functionality intact.

Stop immediately and revert to the last green state. Refactoring should never change external behavior, so failing tests indicate an unintended side effect. Review the change, fix it to preserve original behavior, and re-run tests before proceeding or committing.