testing-strategies

Structure unit and integration tests in Vitest using the Arrange-Act-Assert pattern, keeping tests isolated with fresh setup and teardown, and running parameterized cases to cover edge conditions with focused assertions.

The best way to mock external API dependencies during testing is using MSW-style request mocking and Vitest mocks to control external behaviors, ensuring your tests remain isolated and deterministic.

Use Playwright end-to-end testing instead of unit tests when you need to validate complete user flows with browser automation, following testing pyramid guidance to balance confidence and execution speed.

Ensure integration tests repeat correctly with database state changes by resetting the database state during the setup and teardown phases, which guarantees a clean, isolated environment for every test run.

You can set measurable coverage goals for React component testing by defining target metrics within your test plan, organizing tests by type, and establishing quality gates to prevent regressions.

End-to-end tests fail to isolate user flow checks when external dependencies are not properly mocked, requiring you to implement MSW-style request mocking to control API responses and ensure reliable Playwright browser automation verification.