write-testslisted

# Writing unit tests Unit tests in these projects are **pure-logic tests**: node environment, a minimal mocked `react-native`, no renderer. The standard: test non-trivial business logic (merge, persist, sync, eligibility, verification, ordering, edge-case utils) with small fixture builders; never write trivial assertion-only tests. ## Step 1 — read the repo's test setup before writing anything Never assume the config. These repos commonly have **two** Jest configs and only one of them is the real unit-test path. 1. Read `package.json` scripts. Look for a dedicated unit script (often `test:unit`) pointing at its own config (often `jest.unit.config.js`). A bare `test` script using the `react-native` preset is usually *not* where the tests live — check which config the existing tests actually match. 2. Read that config and note: - `testEnvironment` — typically `node`, meaning no jsdom and no native runtime. - **`testMatch`** — this is the trap. If it is `['**/*.test.ts']`, a `.test.tsx` file is **silently skipped**. Component/JSX tests are then not supported at all, and naming a file `.test.tsx` ships an unrun test that looks green. - `setupFiles` — read the setup file and list what it mocks globally. 3. Read 2–3 existing test files near the code you are testing. Mirror their imports, fixture style, and naming exactly. A typical setup file globally mocks: `__DEV__ = false`; `react-native` down to just `{ NativeModules: {}, Platform }` wit