Testing

The stack

Vitest + React Testing Library for unit and integration tests. Files: src/**/*.test.ts(x). Setup in src/test/setup.ts (mocks for next-intl, next/navigation, Sentry).
Playwright (Chromium) for end-to-end tests. Files: e2e/**/*.spec.ts. It starts the dev server automatically when run locally.

pnpm test          # watch mode
pnpm test:run      # run once
pnpm test:coverage # with coverage
pnpm test:e2e      # Playwright E2E

What each layer tests

Test type follows the layer being changed:

Layer	Test type
`src/lib/**`	Vitest unit tests
`src/server/routers/**`	Vitest integration (mocked Prisma + auth context)
`src/components/**`	React Testing Library
User-visible flows	Playwright E2E

Definition of done

Testing in this kit is a development requirement, not an afterthought:

Every new feature ships with its tests in the same change. A feature with failing, skipped, or missing tests is an open task, not a finished one.
pnpm test:run and pnpm lint green are part of the deliverable.
Bug fixes add a regression test that fails before the fix and passes after.
Behavior changes update the affected tests. If you change what code does and every test still passes untouched, that's a red flag — the suite is tolerating the change through passive mocks instead of asserting it.
Never weaken a test to make it pass — no deleting assertions, loosening matchers, or adding .skip. If a test no longer reflects intended behavior, rewrite it for the new intent in the same change.

Writing tests against org-scoped routers

Integration tests mock Prisma and the auth context, then assert both the happy path and the isolation guarantees — e.g. that a query filters by organizationId and that the wrong tier is rejected. The existing router tests in src/server/routers/*.test.ts are the pattern to copy.

Parity test

messages-parity.test.ts asserts that en.json and es.json have identical keys. Add a translation to only one file and the suite goes red — a cheap guard against half-translated UI (see Internationalization).