testing-strategy-architect

Install vitest, @vitejs/plugin-react, jsdom, and Testing Library packages, then create a vitest.config.ts with the jsdom environment, globals enabled, and a setupFiles entry. Add a setup file that imports jest-dom matchers and registers cleanup after each test.

Define handlers using http.get and http.post from msw, returning HttpResponse.json payloads, then create a server with setupServer from msw/node. Start it in your Vitest setup file with onUnhandledRequest set to error, and override handlers per test with server.use.

Mock the database and auth modules with vi.mock before importing the action, providing mocked implementations for Prisma models and the auth function. Then call the action directly and assert on the mocked calls and returned results, including unauthenticated rejection cases.

The recommended configuration sets 80% for lines and functions and 70% for branches using the v8 coverage provider. Unit tests should target 90% or more for utilities, component tests 80% for interactive components, and e2e tests should cover only critical paths.

Use Playwright only for critical user journeys like authentication, checkout, and core workflows, typically 10 to 20 slow high-confidence tests. Component tests with Testing Library cover interactions, error states, and accessibility much faster and should make up the bulk of the suite.