# Vitest

Set up Vitest testing in any project, detects type (Cloudflare Workers, React, Node...

- Repository: https://github.com/jezweb/claude-skills (1094 stars)
- Category: Testing
- License: MIT
- Last updated: 2026-10-09
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add jezweb/claude-skills --skill vitest -g -a claude-code -y`
Codex: `npx skills add jezweb/claude-skills --skill vitest -g -a codex -y`
Cursor: `npx skills add jezweb/claude-skills --skill vitest -g -a cursor -y`
Gemini CLI: `npx skills add jezweb/claude-skills --skill vitest -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add jezweb/claude-skills`

## Description

Set up Vitest testing in any project, detects type (Cloudflare Workers, React, Node, library), generates vitest.config.ts, test setup, utilities, and a sample test. Covers mocking patterns, coverage config, workspace setup, Jest migration. Use whenever the user mentions adding tests, setting up Vitest, configuring tests, migrating from Jest, fixing testing infrastructure, or asks 'how do I test this'.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Vitest Setup

Detect the project type, generate the right Vitest configuration, and produce working test infrastructure. Not a reference card, this skill creates files.

## Workflow

1. **Detect**, scan the project to determine type and existing setup
2. **Configure**, generate vitest.config.ts tailored to the environment
3. **Scaffold**, create test setup, utilities, and a sample test
4. **Wire up**, add package.json scripts and TypeScript config

## Step 1: Detect Project Type

Read these files to determine the project:

```
package.json          → dependencies, scripts, type field
tsconfig.json         → paths, compiler options
wrangler.toml         → Cloudflare Workers project
vite.config.ts        → existing Vite setup (extend, don't replace)
vitest.config.ts      → already configured? just fill gaps
jest.config.*         → migration candidate
src/                  → source structure
```

Classify as one of:

| Type | Signals | Environment |
|------|---------|-------------|
| **Cloudflare Workers** | wrangler.toml, @cloudflare/workers-types, cloudflare vite plugin | `node` with Workers-specific setup |
| **React (Vite)** | @vitejs/plugin-react, react-dom | `jsdom` or `happy-dom` |
| **React (SSR/TanStack Start)** | @tanstack/start, vinxi | Split: `node` for server, `jsdom` for client |
| **Node/Hono API** | hono, express, no react-dom | `node` |
| **Library** | exports field, no framework deps | `node` |

If a `vite.config.ts` already exists, extend it rather than creating a separate vitest.config.ts, Vitest reads Vite config natively.

## Step 2: Install Dependencies

Generate the install command based on detected type:

```bash
# Base (always)
pnpm add -D vitest

# React projects, add jsdom and Testing Library
pnpm add -D @vitest/coverage-v8 jsdom @testing-library/react @testing-library/jest-dom @testing-library/user-event

# Workers projects, add Cloudflare test utilities
pnpm add -D @vitest/coverage-v8 @cloudflare/vitest-pool-workers

The rest: https://github.com/jezweb/claude-skills/blob/HEAD/plugins/dev-tools/skills/vitest/SKILL.md