grist-mcp-server: Skill for Claude Code

.claude/skills/javascript-testing-patterns/SKILL.md

javascript-testing-patterns is a skill for Claude Code from gwhthompson/grist-mcp-server. It costs 63 tokens per session (6,351 once invoked), scanned B, original, no licence file.

A guide for testing JavaScript and TypeScript code with Jest, Vitest, and Testing Library. It covers small unit tests, tests of combined parts, browser-style end-to-end tests, and TDD, a method of writing tests before code.

In plain words
What is it for?
Use it when writing tests, setting up test infrastructure, or following TDD or BDD workflows.
Why use it?
It helps you choose and organise tests instead of building testing setup and patterns from scratch.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is gwhthompson/grist-mcp-server's own configuration. It tells Claude Code how to work on grist-mcp-server itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything grist-mcp-server configures →

Reuse

Borrowing it

Nothing to install: this file belongs to gwhthompson/grist-mcp-server. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/gwhthompson/grist-mcp-server/master/.claude/skills/javascript-testing-patterns/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/gwhthompson/grist-mcp-server

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for javascript-testing-patterns

README.md
[![agentmods](https://agentmods.dev/badge/skills/gwhthompson/grist-mcp-server/javascript-testing-patterns/github.svg)](https://agentmods.dev/skills/gwhthompson/grist-mcp-server/javascript-testing-patterns)
Your own site
<a href="https://agentmods.dev/skills/gwhthompson/grist-mcp-server/javascript-testing-patterns"><img src="https://agentmods.dev/badge/skills/gwhthompson/grist-mcp-server/javascript-testing-patterns/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for javascript-testing-patterns

Your own site · 80×15
<a href="https://agentmods.dev/skills/gwhthompson/grist-mcp-server/javascript-testing-patterns"><img src="https://agentmods.dev/badge/skills/gwhthompson/grist-mcp-server/javascript-testing-patterns.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 63 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 6,351 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00063 $0.06351
Opus 5.5 $0.00025 $0.02540
Sonnet 5.5 $0.00013 $0.01270
Haiku 4.5 $0.00006 $0.00635

Measured 2mo ago against content hash 91bd0860da65, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade B, and why

javascript-testing-patterns scanned grade B with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Sends data to an external URLmediumData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

const response = await fetch('https://api.example.com/users', { method: 'POST',
.claude/skills/javascript-testing-patterns/SKILL.md · 1,026 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2mo ago First seen · 1,026 lines · 63 tokens per session scan B 91bd0860da65

Subscribe to this mod's changes

javascript-testing-patterns is a skill published in the GitHub repository gwhthompson/grist-mcp-server (4 stars, last pushed 9mo ago), with no licence file. It adds 63 tokens to every session and 6,351 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it B with 1 finding (sends data to an external url). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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