# Rn Write Tests

> Use to write tests for an Expo + RN app: Jest + React Native Testing Library for unit/integration (components, hooks, queries, mutations) and Maestro for end-to-end flows (sign-in, navigation, forms). Sets up the testing stack on first call (jest-expo preset, RNTL, jest config) and writes a focused test next to the source file. Triggers on: "write tests for X", "add e2e test", "mock expo-notifica…

- **Type:** Skill
- **Install:** `agentstack add skill-lukedj78-dev-flow-rn-write-tests`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [lukedj78](https://agentstack.voostack.com/s/lukedj78)
- **Installs:** 0
- **Category:** [Developer Tools](https://agentstack.voostack.com/c/developer-tools)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [lukedj78](https://github.com/lukedj78)
- **Source:** https://github.com/lukedj78/dev-flow/tree/main/rn-write-tests

## Install

```sh
agentstack add skill-lukedj78-dev-flow-rn-write-tests
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# rn-write-tests — Jest + RNTL + Maestro testing for Expo + RN

## Contract

See `references/contracts.md` (vendored from `dev-flow`). Key facts:
- Reads `/.workflow/meta.json#stack.framework` — must be `"expo-rn"`.
- Adds dev dependencies + Jest config on first call (idempotent: detects existing setup).
- Writes test files under `/__tests__/` (Jest convention) for unit/integration.
- Writes Maestro YAML flows under `/.maestro/` for e2e.
- Does NOT modify `meta.json#phase`.

## When this skill applies

- User asks to write a test for a specific source file or flow.
- Orchestrator does NOT route here automatically — test writing is on-demand.

## Knowledge dependencies (read these first)

- `rn-fundamentals/SKILL.md` — TS strict, modern primitives the tests will see.
- `rn-data-fetching/references/patterns.md` — query/mutation patterns the tests must exercise.

## Workflow

### Step 1 — Verify preconditions

Read `.workflow/meta.json`. Abort if `stack.framework != "expo-rn"`.

### Step 2 — Detect / install the test stack

Check if `jest`, `jest-expo`, `@testing-library/react-native` are in `package.json`. If not:

```bash
npx expo install --dev \
  jest jest-expo \
  @testing-library/react-native \
  @testing-library/jest-native \
  @types/jest -- --legacy-peer-deps
```

(See `references/jest-setup.md` for the full config.)

For Maestro: detect `.maestro/` directory. If missing AND user wants e2e, see `references/maestro-setup.md` (manual install, not npm).

### Step 3 — Choose what to test

Ask the user (one round-trip) what to test:
- **Component** (renders, props, interactions) → RNTL.
- **Hook** (`useQuery`, `useMutation`, custom hook) → RNTL `renderHook`.
- **Pure function** (utility, helper) → plain Jest.
- **e2e flow** (sign-in, navigation, form submit) → Maestro.

If the file under test is `lib/api.ts`, write a Jest test of the function with `fetch` mocked.
If the file under test is `app/(auth)/sign-in.tsx`, write an RNTL test of the screen + a Maestro flow of the user journey.

### Step 4 — Write the test

Use the canonical patterns from `references/rntl-patterns.md` (or `references/jest-setup.md` for utilities, or `references/maestro-setup.md` for e2e).

Test files:
- Unit/integration: `__tests__/.test.tsx` (or `.test.ts` for non-JSX).
- e2e: `.maestro/.yaml`.

### Step 5 — Run the test

```bash
cd  && npm test -- --runInBand --bail
```

(For Maestro: `maestro test .maestro/.yaml`.)

Test MUST pass. If it doesn't:
1. Read the failure. Is it a missing mock? An assumption about the test API?
2. Fix the test (NOT the source — that's a separate task).
3. Re-run.

### Step 6 — Commit

```bash
git add __tests__/.test.tsx
git commit -m "test(): cover "
```

## Common anti-patterns (NEVER do)

- ❌ **Detox** — heavy, Expo Go unfriendly, requires native build. Use Maestro.
- ❌ **Enzyme** — abandoned. RNTL only.
- ❌ Snapshot for every component — only for stable design-system primitives.
- ❌ `jest.fn()` without typing the return → tests pass on wrong shape.
- ❌ Testing implementation details (state names, internal function calls) → brittle. Test user-facing behavior.
- ❌ Testing TanStack Query result shape directly → mock the queryFn instead and assert UI.
- ❌ Skipping cleanup → tests leak state. Always use RNTL's auto-cleanup (default).
- ❌ Sleeping `await new Promise(r => setTimeout(r, 1000))` → use `waitFor` with explicit assertions.

## Updating meta.json (recommended pattern)

This skill does NOT advance `meta.json#phase` (see Contract above) — never call `set-phase`. It only records the artifact and appends history, using the canonical script when available:

```bash
# Wherever dev-flow is installed (e.g. ~/.claude/skills/dev-flow/), invoke:
python3 .../dev-flow/scripts/update_meta.py  record-artifact \
    --path  --produced-by '' [--derived-from   ...]
python3 .../dev-flow/scripts/update_meta.py  append-history \
    --skill '' --inputs '{...}' --outputs '{...}' --phase-after 
```

The script normalizes legacy kebab-case aliases (e.g. `module-added` → `module_added`) and writes the canonical sha256 + timestamp into `meta.json#artifacts`. **Fall back to direct JSON editing only if the script is not on PATH** (and warn the user).

## Sources

- Course: codewithbeto.dev/rnCourse — "Testing" module (paid, distilled).
- Official: https://callstack.github.io/react-native-testing-library/
- Official: https://docs.expo.dev/develop/unit-testing/
- Official: https://maestro.mobile.dev/

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [lukedj78](https://github.com/lukedj78)
- **Source:** [lukedj78/dev-flow](https://github.com/lukedj78/dev-flow)
- **License:** MIT

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-lukedj78-dev-flow-rn-write-tests
- Seller: https://agentstack.voostack.com/s/lukedj78
- Browse the marketplace: https://agentstack.voostack.com/browse

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