tdd SKILL.md skillA
tdd from gufranco/claude-engineering-rules is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add gufranco/claude-engineering-rules/tdd@git:20261028.af4ca3ePins git:20261028.af4ca3e in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- gufranco/claude-engineering-rules
- Path
skills/tdd/SKILL.md- Versions recorded
- 5
- Latest version
- git:20261028.af4ca3e, committed Oct 28, 2026
- First version recorded
- Jul 28, 2026
- Size
- 8,904 bytes
- Repository stars
- 3
- License
- MIT
Red-green-refactor TDD loop for a single behavior. Writes a failing test first, runs it to confirm red, implements minimum code to make it green, then refactors with the test as a safety net. Use when user says "tdd", "test first", "red green refactor", "write the test first", or wants a disciplined test-first cycle. For bulk test backfill, use /test; for debugging existing failures, use /investigate; for planning a feature, use /plan.
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
## Overview
Red-green-refactor loop. One behavior at a time. The test must fail before any production code is written.
## When to Use
- The user says "tdd", "test first", "red green refactor", or "write the test first".
- One behavior is small enough to state in a single sentence with a single observable outcome, such as `/tdd user.create rejects empty email`.
- A bug fix needs a reproduction test that fails before the fix lands.
For backfilling tests over existing code, use `/test`; for diagnosing a failure that already exists, use `/investigate`; for designing a feature before the first cycle, use `/plan`.
## Anti-pattern: write-all-tests-then-all-code
Never write the full test suite first and then implement against it in one batch. That pattern produces tests that describe an imagined shape, not the actual behavior the code ends up needing. The tests pass on shape and fail on behavior; they fail on shape and pass on behavior. Either way they stop being a safety net.
Always work in vertical slices: one test, then the smallest implementation that turns the test green, then the next test.
```mermaid
flowchart LR
A[test 1 red] --> B[impl 1 green]
B --> C[test 2 red]
…Read the whole file at its exact version.
How to install
mdr add gufranco/claude-engineering-rules/tdd@sha256:b56e2ac5b4e7d8f0The line at the top of this page pins the label git:20261028.af4ca3e, 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_6ajhgca6cfhgdmbu)
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Versions
The registry has recorded 5 versions of this file, between Jul 28, 2026 and Oct 28, 2026, about one every 23 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20261028.af4ca3e latest | 2026-10-28 | af4ca3e | 8,904 B | A | view · diff |
| git:20261013.7233f74 | 2026-10-13 | 7233f74 | 8,922 B | A | view · diff |
| git:20261012.d086513 | 2026-10-12 | d086513 | 8,747 B | A | view · diff |
| git:20260731.0da2c42 | 2026-07-31 | 0da2c42 | 5,903 B | A | view · diff |
| git:20260728.8a9b2fb | 2026-07-28 | 8a9b2fb | 5,746 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 (8904 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
gufranco/claude-engineering-rules · 3 stars · license MIT · pushed 2026-10-30 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_6ajhgca6cfhgdmbu GET https://markdownregistry.com/api/v1/resolve?ref=gufranco/claude-engineering-rules/tdd GET https://markdownregistry.com/api/v1/blob/b56e2ac5b4e7d8f0e730c8cddfa2020950f0672589d8e4d28ccc0d5b2ee346c7
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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