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.cursor/rules/testing.mdc

Cursor testing rule for Expo

A Cursor `.mdc` rule can attach only when you touch tests. This variant keeps testing policy out of the always-on project rule so day-to-day edits stay quieter. This copy is written for a Expo project. This repository is an Expo React Native app. JavaScript stays portable. Native modules are the ones Expo or the project already configured. Do not eject unless the task says to.

The example uses a balanced, readable style, pragmatic tests, and comments only where the intent is not obvious. Open the generator to make the agent stricter, switch to test-first, quiet the comments, or pick a different file.

The example assumes Expo with React Native. It does not assume Expo Router versus React Navigation unless the repo already picked one. Do not add a bare workflow change casually.

Customize in the generatorBrowse the library

Example file

Balanced strictness, readable style, pragmatic tests. Download name: testing.mdc

---
description: "Testing rules for a Expo repository"
globs: "**/*.{test,spec}.{ts,tsx}"
alwaysApply: false
---

# Testing rules

Attach these rules when editing tests in this Expo repository.
The always-on project rule still lives in `.cursor/rules/project.mdc`. This file does not repeat it.

## Stack

This repository is an Expo React Native app. JavaScript stays portable. Native modules are the ones Expo or the project already configured. Do not eject unless the task says to.

## Commands

- Dev: `npx expo start`
- Lint: `npm run lint`
- Tests: `npm test`

Use the script the repo already defines when it differs from the command above.

## Testing

Add or update tests when behavior changes.

Test hooks and pure logic in Jest. Do not require a device for a data-transform change.

## Done when

- The requested behavior works.
- The screen renders in Expo and `npm test` passes if the repo has tests.
- The diff stays inside the task.
- You list anything you could not run.

Add it to the project

  1. 01

    Copy a starting file

    Copy the example Cursor testing rule on this page, or open the generator if you want different testing, strictness, or comment rules.

  2. 02

    Save it at .cursor/rules/testing.mdc

    Save it at `.cursor/rules/testing.mdc` in the Expo repo, next to the always-on project rule. Leave `alwaysApply` false so it only joins test edits.

  3. 03

    Start a fresh agent session

    Rules files are read when a session starts. A chat that is already open may still be using the old instructions.

  4. 04

    Give it one small task

    Ask for one change a Expo agent often gets wrong, such as a screen that uses a native module the project already depends on, with a loading state. If it ignores the file, confirm the path and start a new session.

Questions about this file

Where do I put Cursor testing rule in a Expo repo?

Save it at `.cursor/rules/testing.mdc` in the Expo repo, next to the always-on project rule. Leave `alwaysApply` false so it only joins test edits.

Which tools read this Cursor testing rule?

Cursor loads `.cursor/rules/testing.mdc` when a file matches its globs. It does not replace `project.mdc`. Keep the always-on rule for stack conventions.

What does the Expo example assume?

The example assumes Expo with React Native. It does not assume Expo Router versus React Navigation unless the repo already picked one. Do not add a bare workflow change casually.

Does VibeSpell upload my repository?

No. Recipe pages are static, and the generator builds the file in your browser from the options you pick. Your source code never leaves the machine.

Other files for Expo

Cursor testing rule for other stacks