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test-driven-development SKILL.md skillA

test-driven-development from endorphin-ai/hasbrains-agent-kit is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.

Install it, pinned

mdr add endorphin-ai/hasbrains-agent-kit/test-driven-development@git:20260731.4cba6d1

Pins git:20260731.4cba6d1 in mdr.lock. Pin the fingerprint instead.

Audit grade: A, 17 of 17 checks passed
Kind: SKILL.md skill
Repository: endorphin-ai/hasbrains-agent-kit
Path: agent-engineering/skills/test-driven-development/SKILL.md
Versions recorded: 2
Latest version: git:20260731.4cba6d1, committed Jul 31, 2026
First version recorded: Jul 3, 2026
Size: 13,434 bytes
Repository stars: 9
License: MIT

Use when implementing any feature or bugfix, in any language or framework, before writing implementation code — write the test first, watch it fail, then write minimal code to pass. Covers the red-green-refactor loop, test-quality principles, rationalization counters, and test-layer selection.

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.**

This skill is language-agnostic. Wherever it says "test runner", use your stack's tool (Jest, pytest, RSpec, go test, JUnit, cargo test, …). Wherever it shows pseudocode, translate to your language's testing idiom.

## When to Use

**Always:**

- New features
- Bug fixes
- Refactoring
- Behavior changes

**Exceptions (ask your human partner):**

- Throwaway prototypes
- Generated code (scaffolds you immediately rewrite)
- 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 the tests. Period.

## Red-Green-Refactor

```dot
digraph tdd_cycle {
    rankdir=LR;
…

Read the whole file at its exact version.

How to install

The exact contents, by fingerprint

mdr add endorphin-ai/hasbrains-agent-kit/test-driven-development@sha256:a7fe22aa9e69874f

The line at the top of this page pins the label git:20260731.4cba6d1, 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.

Badge

[![mdr](https://markdownregistry.com/badge/art_rci2l47cunh4zckg.svg)](https://markdownregistry.com/a/art_rci2l47cunh4zckg)

3 badge image fetches in 30 days. What the badge shows.

Versions

The registry has recorded 2 versions of this file, between Jul 3, 2026 and Jul 31, 2026, about one every 29 days.

version	committed	commit	size	audit
git:20260731.4cba6d1 latest	2026-07-31	4cba6d1	13,434 B	A	view · diff
git:20260703.877e272	2026-07-03	877e272	13,379 B	A	view

Audit of the latest version

A 17 of 17 checks passed. Fixed automatic checks with no AI involved, so the same checks give the 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 (13434 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

endorphin-ai/hasbrains-agent-kit · 9 stars · license MIT · pushed 2026-10-13 · branch main

API

GET https://markdownregistry.com/api/v1/artifacts/art_rci2l47cunh4zckg
GET https://markdownregistry.com/api/v1/resolve?ref=endorphin-ai/hasbrains-agent-kit/test-driven-development
GET https://markdownregistry.com/api/v1/blob/a7fe22aa9e69874f723bcec83511e7106943abdf9a43c3f42d53087726973ad9

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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