Test-Driven Development
Write the failing test first — the red-green-refactor loop for any logic, bug fix, or behavior change
- What
- Write the failing test first — the red-green-refactor loop for any logic, bug fix, or behavior change
- Cost
- Free
- Needs
- a codebase with a test runner
- Install
- Copy the installer prompt below into your Muse — your agent does the rest.
Curated by Skill Harbor — a TDD skill from Addy Osmani's engineering workflow collection: write a failing test before the code that makes it pass, reproduce every bug with a test before fixing it. Its key discipline is stack discovery first — the red-green-refactor cycle is universal but the commands are not, so it teaches the agent to find the repo's own test commands (gradlew, pytest, cargo test, make test) instead of assuming npm test. Distinct from the already-published `mattpocock-tdd` — different creator, and this one is built around the Prove-It Pattern plus browser-test pairing via Chrome DevTools MCP. By @addyosmani, listed here with credit to its creator. Honest caveats: it deliberately skips TDD for pure config, docs, or static content changes; "seems right" is not done — which means it will slow you down on purpose, and that's the point. Skill Harbor never reviews the code, review it yourself before use.
Version:
Install
Prerequisites: a codebase with a test runner Install "Test-Driven Development" for me. Write the failing test first — the red-green-refactor loop for any logic, bug fix, or behavior change Repository: https://github.com/addyosmani/agent-skills/blob/main/skills/test-driven-development/SKILL.md 1. Fetch the SKILL.md file for the addyosmani-test-driven-development skill from the repository into a temporary folder and summarize what it does in one or two sentences. 2. Safety check: review the SKILL.md and scripts for anything suspicious (unexpected network calls, shell commands, credential harvesting). This repo should contain zero secrets in code, credentials only via the secure vault, allowed hosts declared in the SKILL.md. Verify that holds here; STOP on any red flag and tell me. 3. Install it as a skill: copy SKILL.md and its helper files into the agent's skills directory, in a folder named "addyosmani-test-driven-development". 4. Verify with no network calls: frontmatter valid, files in place. 5. Report what was installed, where, and what I still need to do myself (e.g. any accounts, API keys, or CLI tools mentioned in the prerequisites above). GitHub is optional: if I have a GitHub account or the gh CLI, you may use it; otherwise public access is fine. Never require it unless it's in the prerequisites above. Rules: don't touch anything outside the temp folder and the install target. Never ask me to paste secrets in chat — credentials go through the secure vault or environment variables. If anything looks off, stop and ask me.
Questions
How do I install a build?
Every product page includes a copy-paste install prompt. Paste it into your Muse and it sets the build up for you — no manual configuration.
Where does my money go?
Straight to the seller. Skill Harbor never processes payments: checkout happens on the seller’s own page, usually Stripe.
What does the ✓ next to a creator’s name mean?
It means we confirmed the identity of the person behind the listing. It says nothing about the code itself — always check a build before installing it.