A set of rules for writing and organizing software tests, which check that code behaves as expected.

Use it when creating or reviewing tests, including tests for errors, boundaries, external services, and unusual input.

It provides consistent expectations for coverage, test structure, test data, mocks, flaky tests, and edge cases.

testing — Cursor rule for Cursor by dasomel/oh-my-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.

Clone the repo

git clone --depth 1 https://github.com/dasomel/oh-my-cursor

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/dasomel/oh-my-cursor/testing/github.svg)](https://agentmods.dev/rules/dasomel/oh-my-cursor/testing)

Your own site

<a href="https://agentmods.dev/rules/dasomel/oh-my-cursor/testing"><img src="https://agentmods.dev/badge/rules/dasomel/oh-my-cursor/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/dasomel/oh-my-cursor/testing"><img src="https://agentmods.dev/badge/rules/dasomel/oh-my-cursor/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 372 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	$0.00372
Opus 5.5	$0.00000	$0.00149
Sonnet 5.5	$0.00000	$0.00074
Haiku 4.5	$0.00000	$0.00037

Measured 2mo ago against content hash 7ec2929c8485, 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 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.

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.

rules/practices/testing.mdc · 56 lines

What it actually says

Testing Standards

Coverage Targets

Line coverage: ≥ 80%
Branch coverage: ≥ 75% on critical paths
Function coverage: ≥ 90%

Test Structure (AAA Pattern)

it('should return error when input is empty', () => {
  // Arrange
  const input = ''

  // Act
  const result = validateInput(input)

  // Assert
  expect(result.ok).toBe(false)
  expect(result.error).toBe('Input cannot be empty')
})

Naming

Describe behavior, not implementation: 'should return 404 when user not found'
Not: 'test getUserById with invalid id'

Test Data

Use factories/builders, not hardcoded values
Seed random data with faker for variety
Reset state between tests

Mocking Rules

Mock external dependencies (HTTP, DB, filesystem)
Don't mock your own code (that's testing the mock)
Verify mock calls when behavior matters, not just return values

Flaky Test Prevention

No setTimeout or sleep in tests
Use waitFor with explicit conditions
Deterministic test order (each test is independent)
No shared mutable state between tests

Edge Cases Checklist

Empty/null input
Maximum/minimum boundary values
Unicode and special characters
Concurrent operations
Network timeout/error
Permission denied

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.

2mo ago First seen · 56 lines · 0 tokens per session scan A 7ec2929c8485

Subscribe to this mod's changes

testing is a cursor rule published in the GitHub repository dasomel/oh-my-cursor (3 stars, last pushed 7mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 372 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