Vitest provides fast, modern testing for JavaScript and TypeScript. Here's how to use it effectively.
Setup
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Basic Tests
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Matchers
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Mocking
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Mocking Modules
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Testing Async Code
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Snapshot Testing
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Testing React Components
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Test Utilities
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Best Practices
Organization:
✓ Group related tests
✓ Use descriptive names
✓ Follow AAA pattern (Arrange, Act, Assert)
✓ Keep tests focused
Mocking:
✓ Mock external dependencies
✓ Reset mocks between tests
✓ Avoid mocking too much
✓ Use spies for verification
Performance:
✓ Use concurrent tests
✓ Minimize setup/teardown
✓ Run tests in watch mode
✓ Use coverage reports
Maintenance:
✓ Update snapshots intentionally
✓ Remove obsolete tests
✓ Refactor test code
✓ Document complex setups
Conclusion
Vitest provides fast, modern testing with great TypeScript support and Jest compatibility. Use mocking strategically, leverage concurrent tests for speed, and keep tests focused and maintainable. The watch mode and coverage reports make development feedback loops quick and informative.