test-driven-development SKILL.md skillA
test-driven-development from addyosmani/agent-skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add addyosmani/agent-skills/test-driven-development@git:20261029.2b14012Pins git:20261029.2b14012 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- addyosmani/agent-skills
- Path
skills/test-driven-development/SKILL.md- Versions recorded
- 7
- Latest version
- git:20261029.2b14012, committed Oct 29, 2026
- First version recorded
- Apr 13, 2026
- Size
- 16,845 bytes
- Repository stars
- 112,362
- License
- MIT
Drives development with tests using the red-green-refactor loop. Use when implementing any logic, fixing any bug, or changing any behavior. Use when you need to prove that code works, when a bug report arrives, or when you're about to modify existing functionality. Use when asked to add tests to a function, fix a bug in it or change its behavior, even when the code is pasted inline and the request does not mention tests.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Test-Driven Development ## Overview Write a failing test before writing the code that makes it pass. For bug fixes, reproduce the bug with a test before attempting a fix. Tests are proof — "seems right" is not done. A codebase with good tests is an AI agent's superpower; a codebase without tests is a liability. ## When to Use - Implementing any new logic or behavior - Fixing any bug (the Prove-It Pattern) - Modifying existing functionality - Adding edge case handling - Any change that could break existing behavior **When NOT to use:** Pure configuration changes, documentation updates, or static content changes that have no behavioral impact. **Related:** For browser-based changes, combine TDD with runtime verification using Chrome DevTools MCP — see the Browser Testing section below. ## Discover the Stack First The TDD cycle is universal; the commands are not. Before writing the first test, discover how *this* repository tests, and use its commands for every RED, GREEN, and verification step: - **Language and build system** — `package.json`, `pom.xml`/`build.gradle`, `pyproject.toml`, `go.mod`, `Cargo.toml`, `Gemfile`, a `Makefile` …
Read the whole file at its exact version.
How to install
mdr add addyosmani/agent-skills/test-driven-development@sha256:8fcaa57cf445ca61The line at the top of this page pins the label git:20261029.2b14012, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_vwyc5vacuooqo7yp)
8 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 7 versions of this file, between Apr 13, 2026 and Oct 29, 2026, about one every 33 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20261029.2b14012 latest | 2026-10-29 | 2b14012 | 16,845 B | A | view · diff |
| git:20261011.7c47146 | 2026-10-11 | 7c47146 | 16,676 B | A | view · diff |
| git:20260907.cda4542 | 2026-09-07 | cda4542 | 16,517 B | A | view · diff |
| git:20260807.91d4d07 | 2026-08-07 | 91d4d07 | 16,483 B | A | view · diff |
| git:20260719.2e49319 | 2026-07-19 | 2e49319 | 16,477 B | A | view · diff |
| git:20260507.b765343 | 2026-05-07 | b765343 | 14,976 B | A | view · diff |
| git:20260413.ad35cbf | 2026-04-13 | ad35cbf | 14,896 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (16845 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
addyosmani/agent-skills · 112,362 stars · license MIT · pushed 2026-10-31 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_vwyc5vacuooqo7yp GET https://markdownregistry.com/api/v1/resolve?ref=addyosmani/agent-skills/test-driven-development GET https://markdownregistry.com/api/v1/blob/8fcaa57cf445ca6111fd20d2321bcfc0f424db7cfe526836db7b9bf8828fee39
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.
More from addyosmani/agent-skills
Every file in addyosmani/agent-skills