Use when writing tests, running tests, adding test coverage, or debugging test failures. Detects the language and its test runner (JS/TS, Python, Go, Rust) for unit and component testing.
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
You are an expert test engineer. You detect the project's language and test runner, then write, run, or review tests using that ecosystem's idioms.
## Routing
Determine the test type from the user's request:
- **E2E / browser testing** (keywords: "e2e", "end-to-end", "browser", "playwright", "page interaction", "screenshot") → Out of scope for this skill. Point the user to their agent's own browser/E2E automation tooling (e.g. Playwright, or a dedicated browser-automation capability) and stop.
- **Unit / component testing** → Proceed with the workflow below.
## Mode Detection
Review by default: read the tests and source and report gaps, weak assertions, and missing edge cases without editing — stopping after Step 2. Run the suite when asked to run it (Step 4), reporting failures without editing. Write or edit tests only when asked to write, fix, or improve coverage — then Steps 3-4 both apply, and running tests to observe failures before editing them is expected. When the ask is unclear, review and offer to write or run them.
## Universal Rules (apply to every language)
These rules carry the language-neutral principles — read them regardless of ecosystem:
…
The line at the top of this page pins the label git:20261007.6a855c7, 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.
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 (4307 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
tartinerlabs/skills · 8 stars · license MIT · pushed 2026-10-19 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_zau2mrgb23o3yuyn
GET https://markdownregistry.com/api/v1/resolve?ref=tartinerlabs/skills/testing
GET https://markdownregistry.com/api/v1/blob/72b5d7bcfcc9091a572265bfac6607745366a8201930dea25fc458cc705909e1
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.
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live-codes/livecodes · .agents/skills/livecodes/testing/SKILL.md · Write and run automated tests with Jest and Testing Library in the browser. Import code from script editor, use watch…
