Testing rules for TypeScript projects, including where test files go, how to structure tests, and what kinds of cases to cover.

Use them when writing or reviewing unit and integration tests, including success, error, edge, and boundary cases.

They provide a shared standard so tests are easier to find, understand, maintain, and trust.

testing — Cursor rule for Cursor by arjshiv/localutils-mcp-server

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.

Clone the repo

git clone --depth 1 https://github.com/arjshiv/localutils-mcp-server

Made for: Cursor.

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.

README.md

[![agentmods](https://agentmods.dev/badge/rules/arjshiv/localutils-mcp-server/testing/github.svg)](https://agentmods.dev/rules/arjshiv/localutils-mcp-server/testing)

Your own site

<a href="https://agentmods.dev/rules/arjshiv/localutils-mcp-server/testing"><img src="https://agentmods.dev/badge/rules/arjshiv/localutils-mcp-server/testing/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.

Your own site · 80×15

<a href="https://agentmods.dev/rules/arjshiv/localutils-mcp-server/testing"><img src="https://agentmods.dev/badge/rules/arjshiv/localutils-mcp-server/testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 0 Nothing until a file matches its globs; then the whole rule loads.

When invoked 310 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00000	$0.00310
Opus 5.5	$0.00000	$0.00124
Sonnet 5.5	$0.00000	$0.00062
Haiku 4.5	$0.00000	$0.00031

Measured 1mo ago against content hash 8387da8128f0, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, 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 1mo 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 · 55 lines

What it actually says

Testing Standards

Test Organization

Place tests in __tests__ directory
Name test files with .test.ts or .spec.ts suffix
Group related tests in describe blocks
Use clear, descriptive test names

Test Structure

Follow AAA pattern:
1. Arrange - Set up test data
2. Act - Execute the code being tested
3. Assert - Verify the results

Test Coverage

Aim for 80%+ code coverage
Test both success and error cases
Test edge cases and boundary conditions
Include integration tests for critical paths

Best Practices

Keep tests independent
Avoid test interdependence
Clean up after each test
Use beforeEach/afterEach for setup/teardown
Mock external dependencies

Assertions

Use explicit assertions
One assertion per test when possible
Use appropriate matchers
Include meaningful error messages

Mocking

Mock external dependencies
Use jest.mock() for module mocking
Reset mocks between tests
Verify mock calls when relevant

Test Data

Use factories for test data
Keep test data minimal
Use meaningful test data names
Avoid sharing mutable test data

Performance

Keep tests fast
Avoid unnecessary async operations
Use setup/teardown hooks efficiently
Group similar tests together

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.

1mo ago First seen · 55 lines · 0 tokens per session scan A 8387da8128f0

Subscribe to this mod's changes

testing is a cursor rule published in the GitHub repository arjshiv/localutils-mcp-server (2 stars, last pushed 9mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 310 tokens. 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 2026-08-31.

Testing

testing