Testing rules based on TDD, or test-driven development: write a failing test, add the smallest implementation that passes, then improve the code. They cover unit, integration, and end-to-end tests, plus naming and test-data practices.

Use them when writing or reviewing tests for functions, APIs, databases, and complete user flows, including test files, fixtures, mocks, and coverage.

They create a repeatable way to catch regressions and keep tests independent and understandable.

testing — Cursor rule for Cursor by vibeeval/vibecosystem

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/vibeeval/vibecosystem

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/vibeeval/vibecosystem/testing/github.svg)](https://agentmods.dev/rules/vibeeval/vibecosystem/testing)

Your own site

<a href="https://agentmods.dev/rules/vibeeval/vibecosystem/testing"><img src="https://agentmods.dev/badge/rules/vibeeval/vibecosystem/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/vibeeval/vibecosystem/testing"><img src="https://agentmods.dev/badge/rules/vibeeval/vibecosystem/testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 6 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 208 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	$0.00006	$0.00208
Opus 5.5	$0.00002	$0.00083
Sonnet 5.5	$0.00001	$0.00042
Haiku 4.5	$0.00001	$0.00021

Measured 1mo ago against content hash 1e149138bc3c, 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 · 30 lines

What it actually says

Testing Standards

TDD Workflow (Required)

Write test (RED) - test must FAIL first
Minimal implementation (GREEN) - just enough to pass
Refactor (IMPROVE) - clean up while tests pass
Coverage must be 80%+

Test Types

Unit: Individual functions, utilities
Integration: API endpoints, database operations
E2E: Critical user flows (Playwright)

Naming Convention

Test files: *.test.ts or *.spec.ts
Test names: describe what behavior is expected
Use describe for grouping, it for individual cases

Rules

No console.log in tests
No hardcoded test data -- use factories/fixtures
Mock external services, not internal modules
Each test must be independent (no shared state)

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 · 30 lines · 6 tokens per session scan A 1e149138bc3c

Subscribe to this mod's changes

testing is a cursor rule published in the GitHub repository vibeeval/vibecosystem (536 stars, last pushed 2mo ago), licensed MIT. It adds 6 tokens to every session and 208 once invoked, about $0.0000 per session on Opus 5.5. 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.

Claude Code TDD Testing ai-agents ai-software-team anthropic automation claude

testing