Testing Test Writing

Behavior-focused unit tests with Vitest verify expected outcomes rather than internal implementation details. Write tests that describe what your code should do—like testing a login function returns a user token—using mocks to isolate external dependencies. This approach catches real bugs while keeping tests maintainable as your code evolves.

Playwright E2E tests automate user interactions across your full application stack. Start by identifying core flows—like user login and dashboard navigation—then write tests that simulate these exact steps in a real browser. Configure your test setup files and environment to run consistently, and organize tests by user journey rather than by page.

Yes. Vitest handles unit and component tests with React Testing Library, while Playwright covers end-to-end scenarios. Both integrate into a single testing strategy: Vitest validates logic and component behavior in isolation, Playwright confirms workflows across your full application. Configure both in your project's test setup and naming conventions.

Test API routes and Content Collections by writing unit tests that verify request handling, data validation, and response structure. Use mocks for external dependencies and database calls. Define coverage metrics upfront to ensure tests exercise core user flows and critical functionality paths, not just happy-path scenarios.

Use consistent naming—.test.ts or .spec.ts extensions for Vitest, descriptive names for Playwright suites—and organize files alongside source code or in a dedicated test directory. Include test configuration files like vitest.config.ts and test setup utilities. Clear naming and structure make tests discoverable, maintainable, and easier to run.

Tests that couple to implementation details rather than behavior fail when code changes, even if functionality remains intact. They also miss real bugs because they don't verify expected outcomes. Behavior-focused testing with strategic coverage of critical flows ensures tests catch genuine issues and remain stable through refactors.