Add testing infrastructure with Vitest and Testing Library

.github/workflows/ci.yml

@@ -0,0 +1,34 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+jobs:
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install pnpm
+        uses: pnpm/action-setup@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: pnpm
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Typecheck
+        run: pnpm typecheck
+
+      - name: Test
+        run: pnpm test

README.md

@@ -10,6 +10,7 @@ A generic library template starter for brand new libraries.
 | 🔍 PR Preview          | Optional package preview builds for every PR and commit with [pkg.pr.new](https://github.com/stackblitz-labs/pkg.pr.new) |
 | 🎯 TypeScript Ready    | Full TypeScript support with strict type checking |
 | 🧹 Code Quality        | ESLint and Prettier pre-configured for code quality |
+| 🧪 Testing Ready       | **Vitest** + **Testing Library** pre-configured, with CI running on every PR |
 | ⚛️ React Support       | React support with proper peer dependencies **React 19** + **React Compiler** ready |
 | 🔒 Type Safety         | Strict TypeScript configuration for better type safety |
 
@@ -49,6 +50,22 @@ Then **manually** remove the peerDependencies section from `package.json` and al
 
 <br/>
 
+## 🧪 Testing
+
+This template ships test-ready with [Vitest](https://vitest.dev) and [Testing Library](https://testing-library.com), running in a `jsdom` environment so you can test both plain logic and React components.
+
+```bash
+# Run the suite once
+pnpm test
+
+# Run in watch mode while developing
+pnpm test:watch
+```
+
+Tests live next to the source as `*.test.ts` / `*.test.tsx` files (see `packages/core/*.test.*` for examples). The included `.github/workflows/ci.yml` workflow typechecks and runs the suite on every pull request.
+
+<br/>
+
 ## 🤖 Automatic Workflows
 
 This template comes with two GitHub Actions workflows (currently disabled for convenience):

package.json

@@ -23,6 +23,8 @@
     "build": "tsup",
     "dev": "tsup --watch",
     "typecheck": "tsc --noEmit",
+    "test": "vitest run",
+    "test:watch": "vitest",
     "version:package": "pnpm changeset version",
     "release": "pnpm build && pnpm changeset publish",
     "lint": "eslint -c ./eslint.config.mjs . --fix --no-cache"
@@ -33,6 +35,9 @@
   "devDependencies": {
     "@changesets/cli": "^2.27.11",
     "@eslint/js": "^9.18.0",
+    "@testing-library/dom": "^10.4.1",
+    "@testing-library/jest-dom": "^6.9.1",
+    "@testing-library/react": "^16.3.2",
     "@types/node": "^20.11.24",
     "@types/react": "^19.2.14",
     "@typescript-eslint/eslint-plugin": "^8.21.0",
@@ -43,11 +48,14 @@
     "eslint-plugin-react": "^7.37.4",
     "eslint-plugin-react-compiler": "19.0.0-beta-decd7b8-20250118",
     "globals": "^15.14.0",
+    "jsdom": "^29.1.1",
     "prettier": "^3.4.2",
     "react": "^19.2.4",
+    "react-dom": "19.2.4",
     "tsup": "^8.0.2",
     "typescript": "^5.7.3",
-    "typescript-eslint": "^8.21.0"
+    "typescript-eslint": "^8.21.0",
+    "vitest": "^3.2.6"
   },
   "peerDependencies": {
     "react": ">=16.8.0"

packages/core/core.test.tsx

@@ -0,0 +1,17 @@
+import { render, screen } from '@testing-library/react'
+import { describe, expect, it } from 'vitest'
+
+import { GenericComponent, useGenericHook } from './core'
+
+describe('GenericComponent', () => {
+  it('renders its content', () => {
+    render(<GenericComponent />)
+    expect(screen.getByText('GenericComponent')).toBeInTheDocument()
+  })
+})
+
+describe('useGenericHook', () => {
+  it('returns the expected value', () => {
+    expect(useGenericHook()).toBe('GenericHook')
+  })
+})

packages/core/index.test.ts

@@ -0,0 +1,11 @@
+import { describe, expect, it } from 'vitest'
+
+import { VERSION } from './index'
+import { version } from '../../package.json'
+
+describe('VERSION', () => {
+  it('is exported and matches package.json', () => {
+    expect(VERSION).toBe(version)
+    expect(VERSION).toMatch(/^\d+\.\d+\.\d+/)
+  })
+})