tdd SKILL.md skillA
tdd from youdotcom-oss/agent-skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add youdotcom-oss/agent-skills/tdd@git:20260723.e470633Pins git:20260723.e470633 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- youdotcom-oss/agent-skills
- Path
.agents/skills/tdd/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260723.e470633, committed Jul 23, 2026
- Size
- 3,091 bytes
- Repository stars
- 98
- License
- MIT
Use test-driven development for behavior-changing feature or fix work, and whenever the user mentions TDD, test-first, red-green-refactor, tracer bullets, integration tests, or public-interface behavior tests. Skip for docs-only, path-only rename, formatting-only, or purely mechanical chores unless explicitly requested.
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 ## Core Rule Work in vertical red-green-refactor slices: 1. **RED**: write one test for one observable behavior. 2. **GREEN**: implement the smallest production change that makes that test pass. 3. **REFACTOR**: clean up only while tests are green. Do not write a batch of imagined tests before implementation. Each new test should respond to what the last cycle taught you about the actual behavior and interface. ## Plaited Defaults - Use `bun test` for targeted tests and `bun --bun tsc --noEmit` for the type gate. - Use `test`, not `it`, and organize with `describe`. - Prefer real dependencies and real runtime boundaries over mocks. - Mock only external boundaries such as remote APIs, time, randomness, or rare filesystem cases. - Avoid conditional assertions: assert the branch first, then assert branch-specific values. - Test both branches for conditionals, fallbacks, and error paths. - Exercise public interfaces and runtime contracts rather than private helpers. - Follow applicable repo skills and `AGENTS.md` rules for the touched area. ## When Starting Work …
Read the whole file at its exact version.
How to install
mdr add youdotcom-oss/agent-skills/tdd@sha256:4a36f55baf4b9579The line at the top of this page pins the label git:20260723.e470633, 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_pg7sypv3xouyq7bd)
2 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 1 version of this file, committed on Jul 23, 2026.
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 (3091 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
youdotcom-oss/agent-skills · 98 stars · license MIT · pushed 2026-10-28 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_pg7sypv3xouyq7bd GET https://markdownregistry.com/api/v1/resolve?ref=youdotcom-oss/agent-skills/tdd GET https://markdownregistry.com/api/v1/blob/4a36f55baf4b95799f9c3eb1e234f9565d9c9deaf46d110ef58bc2dab12e4302
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.
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