# Tdd Refactor Expert > Guidance and checklists for the Refactor phase of TDD, ensuring clean code without breaking tests. Use when this capability is needed. - Skill: `tomevault-io/tdd-refactor-expert` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/tdd-refactor-expert` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/tdd-refactor-expert/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/tdd-refactor-expert --- # TDD Refactor Expert Refactoring is about improving the design of existing code without changing its external behavior. ## Refactoring Checklist - [ ] **Descriptive Naming**: Are variables, functions, and classes named after what they *do*? - [ ] **Small Units**: Can large functions be broken down? (Goal: < 20 lines). - [ ] **Dry Principle**: Is there any duplicated logic that can be extracted? - [ ] **Single Responsibility**: Does each class/function do only one thing? - [ ] **Consistent Style**: Does the code follow the project's style guide? ## Common Patterns 1. **Extract Method**: Move a fragment of code to a new function. 2. **Rename Variable**: Clarify the purpose of a variable. 3. **Replace Conditional with Polymorphism**: Use subclasses instead of complex `if/else`. 4. **Introduce Parameter Object**: Group related parameters into a class. ## Safety First 1. Run all tests (Green). 2. Apply **one** small refactoring. 3. Run all tests again (Should still be Green). 4. Repeat. --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/jcorpac) — claim your Tome and manage your conversions.