rn-write-tests

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

Contract

See references/contracts.md (vendored from dev-flow). Key facts:

• Reads <project-root>/.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 <project-root>/__tests__/ (Jest convention) for unit/integration.
• Writes Maestro YAML flows under <project-root>/.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:

npx expo install --dev \
  jest jest-expo \
  @testing-library/react-native@^14 \
  test-renderer@^1 \
  @types/jest -- --legacy-peer-deps

(test-renderer@^1 is a required peer dep of RNTL v14 — it replaced react-test-renderer. Node ^22.13 || >=24 is also required. Native matchers like toBeOnTheScreen() are built into @testing-library/react-native v12.4+ — no separate @testing-library/jest-native needed. See references/jest-setup.md for the full config.)

⚠️ RNTL v14 is async: render, renderHook, fireEvent and act all return Promises and MUST be awaited, and the UNSAFE_* queries are gone. Read the v14 section of references/rntl-patterns.md before writing a test — a missing await produces a test that passes for the wrong reason. Migrating an existing suite: npx codemod@latest rntl-v14-update-deps --target . then npx codemod@latest rntl-v14-async-functions --target ./src.