test-driven-development SKILL.md skillA
test-driven-development from obra/superpowers is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add obra/superpowers/test-driven-development@git:20260919.5bf4e78Pins git:20260919.5bf4e78 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- obra/superpowers
- Path
skills/test-driven-development/SKILL.md- Versions recorded
- 6
- Latest version
- git:20260919.5bf4e78, committed Sep 19, 2026
- First version recorded
- Jun 16, 2026
- Size
- 9,578 bytes
- Repository stars
- 302,424
- License
- MIT
Use when implementing any feature or bugfix, before writing implementation code.
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 (TDD)
## Overview
Write the test first. Watch it fail. Write minimal code to pass.
**Core principle:** If you didn't watch the test fail, you don't know if it tests the right thing.
**Violating the letter of the rules is violating the spirit of the rules.**
## When to Use
**Always:**
- New features
- Bug fixes
- Refactoring
- Behavior changes
**Exceptions (ask your human partner):**
- Throwaway prototypes
- Generated code
- Configuration files
Thinking "skip TDD just this once"? Stop. That's rationalization.
## The Iron Law
```
NO PRODUCTION CODE WITHOUT A FAILING TEST FIRST
```
Write code before the test? Delete it. Start over.
**No exceptions:**
- Don't keep it as "reference"
- Don't "adapt" it while writing tests
- Don't look at it
- Delete means delete
Implement fresh from tests. Period.
## Red-Green-Refactor
```dot
digraph tdd_cycle {
rankdir=LR;
red [label="RED\nWrite failing test", shape=box, style=filled, fillcolor="#ffcccc"];
verify_red [label="Verify fails\ncorrectly", shape=diamond];
green [label="GREEN\nMinimal code", shape=box, style=filled, fillcolor="#ccffcc"];
…Read the whole file at its exact version.
How to install
mdr add obra/superpowers/test-driven-development@sha256:64b03fce4aee5a97The line at the top of this page pins the label git:20260919.5bf4e78, 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_ygwq3lvd52squqiv)
7 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 6 versions of this file, between Jun 16, 2026 and Sep 19, 2026, about one every 19 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260919.5bf4e78 latest | 2026-09-19 | 5bf4e78 | 9,578 B | A | view · diff |
| git:20260724.50025d1 | 2026-07-24 | 50025d1 | 9,905 B | A | view · diff |
| git:20260724.9d8630d | 2026-07-24 | 9d8630d | 9,986 B | A | view · diff |
| git:20260724.b9e75dd | 2026-07-24 | b9e75dd | 9,015 B | A | view · diff |
| git:20260724.e74961c | 2026-07-24 | e74961c | 9,907 B | A | view · diff |
| git:20260616.9ea7e2b | 2026-06-16 | 9ea7e2b | 9,894 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 (9578 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
obra/superpowers · 302,424 stars · license MIT · pushed 2026-10-20 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_ygwq3lvd52squqiv GET https://markdownregistry.com/api/v1/resolve?ref=obra/superpowers/test-driven-development GET https://markdownregistry.com/api/v1/blob/64b03fce4aee5a97a93160cea8111f3ba13a17b7c001db4bd5836d67fd10705d
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 obra/superpowers
Every file in obra/superpowers