testing

A testing rule for a monorepo, which is one repository containing multiple related packages or applications. It requires Vitest tests when behavior changes and describes where tests should live and how different parts of the project should be tested.

In plain words
What is it for?
Use it when adding or changing features to choose the right test location, test environment, mocking approach, and validation commands.
Why use it?
It helps behavior changes come with automated checks and keeps testing consistent across the repository.

Cursor rule for Cursor

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/jasonboy/msw-mcp/testing
Clone the repo
git clone --depth 1 https://github.com/JasonBoy/msw-mcp

Made for: Cursor.

Per session 221 This file is loaded in full into every session.
When invoked 221 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original 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 $0.00221 $0.00221
Opus 5 $0.00111 $0.00111
Sonnet 5 $0.00044 $0.00044
Haiku 4.5 $0.00022 $0.00022

Measured 2d ago against content hash ccd1f21f5c44, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

testing scanned grade A with 0 findings 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 2d 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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/rules/testing.mdc · 18 lines

What it actually says

Testing

When adding or changing features, add or update tests. See AGENTS.md for full conventions.

  • Runner: Vitest v4 — pnpm run test from repo root
  • Files: Co-locate as src/**/*.test.ts (excluded from tsc build)
  • Environments: Node (core, msw-cli, msw-mcp); jsdom (@msw-mcp/client)
  • Patterns: Unit tests with mocks; integration tests only for real WS/HTTP round-trips in core
  • CLI: Test pure logic in msw-cli/src/helpers.ts, not index.ts
  • MCP tools: Inject a fake wsServer.sendMessage — see existing tests in packages/msw-mcp/src/tools/

Before finishing, run pnpm run test (and pnpm run build if types changed).

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. 2d ago First seen · 18 lines · 221 tokens per session scan A ccd1f21f5c44

Subscribe to this mod's changes

testing is a cursor rule published in the GitHub repository JasonBoy/msw-mcp (81 stars, last pushed 2mo ago), licensed MIT. It adds 221 tokens to every session, about $0.0011 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.