testing

A set of testing rules for web applications, using Vitest for unit tests and Playwright for end-to-end tests. It prioritizes server actions, API handlers, authentication, and complex business logic.

In plain words
What is it for?
Use it to decide what to test and to write tests for server actions, API routes, sign-in flows, and complex functions.
Why use it?
It helps developers focus tests on code where failures matter most instead of spending time testing simple presentation code or styling.

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/vibestackdev/vibe-stack/testing
Clone the repo
git clone --depth 1 https://github.com/vibestackdev/vibe-stack

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 226 The whole file, excluding the scripts and references it only reads on demand.
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 $0.00000 $0.00226
Opus 5 $0.00000 $0.00113
Sonnet 5 $0.00000 $0.00045
Haiku 4.5 $0.00000 $0.00023

Measured yesterday against content hash 31df67fbf9c8, 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 yesterday.

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 · 36 lines

What it actually says

Testing Strategy

Use Vitest for unit tests, Playwright for E2E testing.

What to test (prioritized):

  1. Server Actions (they're just functions — easy to test)
  2. API route handlers
  3. Auth flows (most critical)
  4. Complex business logic and utility functions

What NOT to bother testing with unit tests:

  • Simple React leaf components (visual testing is better)
  • Styling logic and Tailwind classes
  • Component boilerplate

Simple Server Action test example:

import { createTodo } from '@/app/actions'
import { expect, test, describe } from 'vitest'

describe('createTodo Server Action', () => {
  test('creates todo for authenticated user', async () => {
    const formData = new FormData()
    formData.set('title', 'Test todo')
    
    const result = await createTodo(formData)
    expect(result.success).toBe(true)
  })
})
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. yesterday First seen · 36 lines · 0 tokens per session scan A 31df67fbf9c8

Subscribe to this mod's changes

testing is a cursor rule published in the GitHub repository vibestackdev/vibe-stack (7 stars, last pushed 2d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 226 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.