vitest

name	vitest
description	Vite integration, ESM support, describe/it/expect, mocking (vi.mock), snapshot testing, coverage, watch mode, CI config.

vitest

Blazing fast unit testing with Vite.

Setup and config

• Vite integration: zero-config for Vite projects
• vitest.config.ts: customize test behavior
• Global setup and teardown
• Environment: node, jsdom, happy-dom

Test structure

• describe, it, test blocks
• expect assertions with matchers
• beforeEach, afterEach, beforeAll, afterAll
• Test filtering with .only, .skip, .todo

Mocking

• vi.mock for module-level mocking
• vi.spyOn for function spies
• vi.fn for fake implementations
• vi.useFakeTimers for time control

Advanced

• Snapshot testing with toMatchSnapshot
• Coverage reports with c8/istanbul
• Watch mode with --ui
• CI: --reporter=junit, --reporter=json