---
paths:
  - "**/nuxt.config.*"
  - "**/server/**/*.ts"
  - "**/pages/**"
  - "**/layouts/**"
  - "**/middleware/**"
---

# Nuxt Testing

> This file extends [common/testing.md](../common/testing.md) with Nuxt specific content.

Package: `@nuxt/test-utils`. Vitest-first for unit and component tests, with built-in Playwright browser E2E support. nuxt-vitest and vitest-environment-nuxt are superseded and folded into it.

## Setup

- Install dev deps: `@nuxt/test-utils vitest @vue/test-utils happy-dom playwright-core`.
- Config: `defineVitestConfig({ test: { environment: 'nuxt' } })` from `@nuxt/test-utils/config`. Use `defineVitestProject` for multi-project (separate unit / nuxt / e2e environments).
- Add `@nuxt/test-utils/module` to `nuxt.config`. Per-file opt-in via `// @vitest-environment nuxt`.

## Runtime helpers

Import from `@nuxt/test-utils/runtime`.

- `mountSuspended(component, opts)` mounts in the Nuxt env with async setup + plugin injection (accepts `@vue/test-utils` mount options + `route`).
- `renderSuspended(component, opts)` is the Testing Library variant (needs `@testing-library/vue`).
- `mockNuxtImport(name, factory)` mocks auto-imports (e.g. `useState`). Once per import per file, use `vi.hoisted()`.
- `mockComponent(name, factory)` mocks by PascalCase name or path.
- `registerEndpoint(path, handler|opts)` mocks a Nitro endpoint to test server routes or stub the backend. Supports method + `once`.

## E2E helpers

Import from `@nuxt/test-utils/e2e`.

- `await setup({ rootDir, server, browser, ... })` inside the describe block (manages beforeAll/afterAll).
- Then `$fetch(url)` (rendered HTML), `fetch(url)` (response object), `url(path)` (full URL with port), `createPage(url)` (Playwright).
- Playwright integration: import `expect` / `test` from `@nuxt/test-utils/playwright`.

## What to test how

- Composables: mock auto-imports with `mockNuxtImport`, mount a host component via `mountSuspended` to exercise `useState` / `useFetch` in the Nuxt runtime.
- Server routes: `registerEndpoint` to stub, or e2e `$fetch` / `fetch` against the real Nitro server.

## Reference

- ECC skills: `nuxt4-patterns`, `e2e-testing`, `vite-patterns`.
- [Nuxt testing docs](https://nuxt.com/docs/getting-started/testing)
- [@nuxt/test-utils npm](https://www.npmjs.com/package/@nuxt/test-utils)