Testing Vitest

Vitest is a fast unit testing framework for JavaScript projects. Write tests by creating `.test.js` or `.spec.js` files, import your code and Vitest utilities, define test cases with `describe` and `it`, and use assertions to verify behavior. Vitest integrates seamlessly with modern tooling and runs tests in parallel for quick feedback.

Organize tests in dedicated test directories mirroring your source structure, name test files with `.test.js` or `.spec.js` suffixes, and group related tests with `describe` blocks. Use clear, descriptive test names that explain what behavior is being verified. This structure enforces consistency across codebases and makes tests easier to maintain and discover.

Vitest provides built-in mocking utilities and assertion methods. Use `vi.mock()` to mock modules, `vi.fn()` to create mock functions, and chain assertion methods like `.toEqual()`, `.toHaveBeenCalled()`, and `.toBeDefined()`. Establish setup and teardown with `beforeEach` and `afterEach` hooks to isolate test state and ensure reliable, predictable test execution.

Yes, Vitest supports integration tests alongside unit tests within the same framework. Configure coverage thresholds in `vitest.config.js`, integrate Vitest with CI systems like GitHub Actions or GitLab CI by running `vitest` in your pipeline, and collect coverage reports to enforce code quality standards across your project.

Set coverage thresholds in Vitest configuration to maintain code quality standards. Common targets include 80% line coverage, 75% branch coverage, and 80% function coverage, adjusted to your project's risk profile. Vitest fails CI builds when thresholds aren't met, ensuring consistent test quality across your codebase.

Create a `vitest.config.js` file to define test environment, coverage settings, mock behavior, and CI integration options. Specify test file patterns, coverage thresholds, and assertion libraries. This centralized configuration enforces consistent testing standards and ensures Vitest aligns with your project's architecture and quality requirements.