Detox

detoxTesting35 lines

End-to-end tests driving the real app on a simulator or device.

Current — as published in v1.3.2. Written by hand for Detox, not generated.

The rule

What belongs here

Only flows where a regression would be unacceptable — sign-in, purchase, the core task the app exists for. Everything a component test can catch belongs in a component test: each E2E test costs minutes of CI on every push.

Selectors

  • Use by.id() with accessibility ids. Unlike component tests, this is the right default — text changes with locale and copy edits.
  • Add the id to the component deliberately, as part of the change.

Waiting

js
await waitFor(element(by.id('pro-badge'))).toBeVisible().withTimeout(10000);

Never sleep(). A fixed delay is slow when the app is fast and flaky when it is not, and it hides the real timing bug.

Isolation

  • device.launchApp({ newInstance: true }) in beforeEach. State leaking between tests produces failures that depend on execution order.
  • Stub the network and third-party SDKs in the E2E build. A test that charges a real card, sends a real email, or pollutes analytics is not a test.

Do not

  • Do not add an E2E test for something a unit test proves.
  • Do not assert on exact copy that product will change next week.
  • Do not delete a flaky test — quarantine it and fix the non-determinism.

As each tool receives it

The same guidance, in the shape each editor reads. Cursor and Claude Code are written separately by hand; the rest are derived from the Cursor rule.

→ .cursor/rules/detox.mdchand-written for this tool
.cursor/rules/detox.mdc
---
description: Detox end-to-end testing conventions
globs: ["e2e/**", ".detoxrc.js"]
alwaysApply: false
---

# Detox

## What belongs here

Only flows where a regression would be unacceptable — sign-in, purchase, the
core task the app exists for. Everything a component test can catch belongs in
a component test: each E2E test costs minutes of CI on every push.

## Selectors

- Use `by.id()` with accessibility ids. Unlike component tests, this is the
  right default — text changes with locale and copy edits.
- Add the id to the component deliberately, as part of the change.

## Waiting

```js
await waitFor(element(by.id('pro-badge'))).toBeVisible().withTimeout(10000);
```

Never `sleep()`. A fixed delay is slow when the app is fast and flaky when it
is not, and it hides the real timing bug.

## Isolation

- `device.launchApp({ newInstance: true })` in `beforeEach`. State leaking
  between tests produces failures that depend on execution order.
- Stub the network and third-party SDKs in the E2E build. A test that charges a
  real card, sends a real email, or pollutes analytics is not a test.

## Do not

- Do not add an E2E test for something a unit test proves.
- Do not assert on exact copy that product will change next week.
- Do not delete a flaky test — quarantine it and fix the non-determinism.

What else this module writes

Selecting Detox contributes more than a rule file — all of it merged with every other module you pick, with conflicts resolved rather than duplicated.

Dependencies
detox^20.51.0dev
Folders
e2e/

Related

needsReact Native
Put this in your repo

Adds Detox to a project this tool generated, without starting over. Files you have hand-edited are left alone.