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test-driven-development skillA

Name: test-driven-development
Author: coco-research

test-driven-development is agent-read markdown (skill) from coco-research/coco: Use when implementing any feature or bugfix, before writing implementation code.

Indexed from public GitHub and served as immutable, content-addressed versions. Install it pinned to an exact SHA-256 with the mdr CLI, and every file is verified against the hash recorded here before it reaches your agent. The deterministic audit below grades the latest version, and the same file always earns the same grade.

What the file says

# Test-Driven Development (TDD)

## Overview

**Announce at start:** "Test-Driven Development skill activated."

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];
…

Read the whole file at its exact version.

How to install

Latest version

mdr add coco-research/coco/test-driven-development@git:20260802.1479e32

Exact content

mdr add coco-research/coco/test-driven-development@sha256:52b8686273908621

Pin to a label to follow the author's releases, or to a sha256 to freeze the exact bytes forever. Either way the resolved hash is written to mdr.lock, and mdr install reproduces it on any machine.

Badge

[![mdr](https://markdownregistry.com/badge/art_qz6fkaasyk6mhcvl.svg)](https://markdownregistry.com/a/art_qz6fkaasyk6mhcvl)

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Versions

version	committed	commit	size	audit
git:20260802.1479e32 latest	2026-08-02	1479e32	9,954 B	A	view · diff
git:20260426.d53cc6c	2026-04-26	d53cc6c	9,934 B	A	view

Audit of the latest version

A 17 of 17 checks passed. Deterministic, no model, same answer every run.

pass: Frontmatter block present
pass: Frontmatter declares a name
pass: Frontmatter declares a description
pass: Size between 200 bytes and 200 KB (9954 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

GitHub

coco-research/coco · 478 stars · license NOASSERTION · pushed 2026-09-25 · branch main

API

GET https://markdownregistry.com/api/v1/artifacts/art_qz6fkaasyk6mhcvl
GET https://markdownregistry.com/api/v1/resolve?ref=coco-research/coco/test-driven-development
GET https://markdownregistry.com/api/v1/blob/52b8686273908621e4e76080616bb8114d3320d94abd34e77f6d1f3893e134d0

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