Agent skill

vitest-dom

Use vitest + jsdom for fast, lightweight unit tests for front-end apps

View SKILL.md on GitHub Repository
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Install this agent skill to your Project

npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/testing/vitest-dom-sanand0-scripts

SKILL.md

  • Use vitest and jsdom for front-end testing.
  • Avoid vitest.config.*; default ESM import works, launch via "test": "npx -y vitest run" in package.json. Add jsdom as a devDependency. Add npm test to prepublishOnly
  • Treat tests as lightweight integration, not unit. Load the full HTML + scripts and verify real DOM mutations; ensures refactors don't silently break UI wiring.
  • Log browser console.* output.
  • Mount local HTML. settings.fetch.virtualServers = [{url:"https://test/", directory: <root>}]. Use page.goto("https://test/...") to load files without a dev-server.
  • Create a fresh page for each test to isolate window, document, etc.
  • Fake timers for deterministic testing.
    • Call vi.useFakeTimers() in beforeAll, vi.useRealTimers() in afterAll.
    • Re-bind window.setTimeout = setTimeout so app code sees the mocked clock.
    • Drive async paths with vi.advanceTimersByTime(ms) instead of await sleep.
  • Stub external APIs with vi.fn() - e.g. window.fetch = vi.fn(() => Promise.resolve({ok:true,...})) avoids network and lets you assert payloads.
  • Spy on side-effects - vi.spyOn(console, "error"), clipboard reads, etc.; always mockRestore() afterwards to prevent bleed-through.
  • Add timeouts per test case, e.g. { timeout: 10_000 }, for long-running tests.

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