# Compound V Tdd > Applies tests-first discipline (red/green/refactor) and adds regression tests for bugs. Use when implementing features, fixing bugs, or refactoring. Use when this capability is needed. - Skill: `tomevault-io/compound-v-tdd` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/compound-v-tdd` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/compound-v-tdd/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/compound-v-tdd --- # TDD Skill **Announce at start:** "Using TDD: writing test first for [behavior]." ## When to use this skill - new features that can be unit tested - bug fixes (always add a regression test if practical) - refactors (protect behavior with tests first) ## Research Before writing tests, do research **in parallel** (invoke multiple tool calls in the same response): - Search the web for the project's testing framework best practices and latest patterns (scope to `stack.md` versions). - Search the web for assertion styles and testing utilities available in the framework. ## Rules - Prefer **red -> green -> refactor**. - If tests are hard, still add **verification**: minimal repro script, integration test, or clear manual steps. - Keep tests focused: one behavior per test where possible. - Name tests by behavior, not implementation details. ## Process 1. Define the behavior change (what should be true after). 2. Write/adjust a test to capture it (make it fail first if possible). 3. Implement the minimal change to pass. 4. Refactor if needed (keep passing). 5. Run the relevant test suite + any linters **in parallel** where they are independent. ## Output requirements When you change code, include: - what tests you added/changed - how to run them - what they prove ## Bite-sized granularity Each step should be one action (2-5 minutes): 1. Write the failing test — step 2. Run it to confirm it fails — step 3. Implement the minimal code to make it pass — step 4. Run tests to confirm they pass — step 5. Commit — step Don't combine these. Each step is independently verifiable. --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/shermanhuman) — claim your Tome and manage your conversions.