vitest-best-practices

Parameterized tests in Vitest use the `it.each` or `test.each` pattern to run the same test logic against multiple inputs. This approach reduces duplication and improves clarity by consolidating repetitive test cases into a single, maintainable structure.

The best way to structure a Vitest test suite is by applying the AAA pattern, organizing tests logically, and using clear naming conventions. This increases clarity and reliability by standardizing the arrangement, action, and assertion phases across the entire project.

Test doubles in Vitest, such as mocks and stubs, should be applied safely by isolating external dependencies. Using safe test double patterns prevents flaky tests by ensuring your unit tests remain deterministic and focused solely on the code under test.

Vitest async tests fail when promises are not properly awaited within the test block. You must handle asynchronous operations correctly by returning the promise or using async/await to ensure the test runner waits for the resolution before completing.

Yes, you can apply Vitest best practices to refactor existing test suites by updating them to use rigorous assertions, parameterized tests, and the AAA pattern. This refactoring process increases clarity, maintainability, and reliability across typical Vitest projects.