test-design SKILL.md skillA

test-design from yarlson/yarstack is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.

Install it, pinned

mdr add yarlson/yarstack/test-design@git:20261017.2f2e03b

Pins git:20261017.2f2e03b in mdr.lock. Pin the fingerprint instead.

Audit grade: A, 17 of 17 checks passed
Kind: SKILL.md skill
Repository: yarlson/yarstack
Path: plugins/yarstack/skills/test-design/SKILL.md
Versions recorded: 6
Latest version: git:20261017.2f2e03b, committed Oct 17, 2026
First version recorded: Jul 18, 2026
Size: 3,555 bytes
Repository stars: 3
License: MIT

Design or write reproducible tests matched to behavioral risk before implementation. Use for product behavior; for tooling or infrastructure, use it only when native checks such as linters, validators, dry runs, or plans cannot show the behavior.

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 Design

Own the prospective test contract and test code, not the production implementation or retrospective evidence audit.

## Workflow

1. Confirm that dedicated automated tests are warranted. For tooling or infrastructure, name the native checks that prove the change and stop, unless those checks cannot show behavior that matters.
2. Identify the authoritative contract, condition, action, observable result, invariants, important side effects, assumptions, and state preserved on failure.
3. Choose the lowest test level that proves the contract through a stable public or system boundary.
4. Match the method to the risk: use examples for concrete cases, property or model-based tests for invariants and sequences, fuzzing for broad or hostile input, and systematic concurrency or fault-injection tests for ordering, restart, and recovery. Select only methods that address a material risk.
…

Read the whole file at its exact version.

How to install

The exact contents, by fingerprint

mdr add yarlson/yarstack/test-design@sha256:3c58429eb6d44c53

The line at the top of this page pins the label git:20261017.2f2e03b, 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_tca34jfeahmf5n6o.svg)](https://markdownregistry.com/a/art_tca34jfeahmf5n6o)

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

Versions

The registry has recorded 6 versions of this file, between Jul 18, 2026 and Oct 17, 2026, about one every 18 days.

version	committed	commit	size	audit
git:20261017.2f2e03b latest	2026-10-17	2f2e03b	3,555 B	A	view · diff
git:20260911.e22616f	2026-09-11	e22616f	3,057 B	A	view · diff
git:20260724.0771972	2026-07-24	0771972	3,003 B	A	view · diff
git:20260724.540bbe9	2026-07-24	540bbe9	2,663 B	A	view · diff
git:20260720.2e4f3b4	2026-07-20	2e4f3b4	2,266 B	A	view · diff
git:20260718.188cd11	2026-07-18	188cd11	1,479 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 (3555 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

yarlson/yarstack · 3 stars · license MIT · pushed 2026-10-19 · branch main

API

GET https://markdownregistry.com/api/v1/artifacts/art_tca34jfeahmf5n6o
GET https://markdownregistry.com/api/v1/resolve?ref=yarlson/yarstack/test-design
GET https://markdownregistry.com/api/v1/blob/3c58429eb6d44c53ee0969c42163c79e2e47fdcac8a195b72946ef2d505f2424

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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