write-tests

name	write-tests
description	Write unit tests following this repo's conventions for backend (NestJS, ts-jest, *.spec.ts) and mobile (jest-expo, *.test.ts, RNFB/native mocking). Use when adding test coverage for services, guards, pipes, hooks, stores, or utilities.

Writing tests

Backend (backend/, *.spec.ts under src/, ts-jest)

• Instantiate plain classes directly with mocked deps: new Service(mockPrisma as never).
• Mock Prisma as a plain object; for $transaction(async (tx) => ...) use $transaction: jest.fn((cb) => cb(tx)) with a tx mock exposing the models used.
• For modules mocked via factory referencing outer vars, name them mock* (jest hoisting allows mock-prefixed names), e.g. const mockVerifyIdToken = jest.fn().
• Test guards by faking ExecutionContext: { switchToHttp: () => ({ getRequest: () => ({ headers: {...} }) }) } as unknown as ExecutionContext.
• Manage process.env with save/restore in beforeEach/afterAll for env-driven code.
• Run: bun run test (config in package.json; testRegex = .spec.ts$).

Mobile (mobile/, *.test.ts(x), jest-expo)

• Do NOT use renderHook — react-test-renderer is incompatible with React 19 here ("Can't access .root on unmounted test renderer"). Instead extract pure logic and test it directly (e.g. resolveLocale is exported from useTranslations).
• Native modules: mock with the mock-prefixed factory pattern, then jest.resetModules() + require('./module') per test to reset module-level state:

  const mockGetToken = jest.fn();
  jest.mock('@react-native-firebase/messaging', () => ({ getToken: mockGetToken, ... }));
  

• AsyncStorage + SecureStore are already mocked in jest.setup.js.
• Zustand stores: drive via store.getState().setX() / store.setState().
• Run: bun run test.

Add a test for any non-trivial logic you add (services/guards/pipes/crypto on backend; pure functions, stores, api/error helpers, push lifecycle on mobile).