# Web Test Runner
Test runner for web applications.
👉 Headless browsers with [Puppeteer](browsers/puppeteer.md), [Playwright](browsers/playwright.md), or [Selenium](browsers/selenium.md).
🚧 Reports logs, 404s, and errors from the browser.
🔍 Debug opens a real browser window with devtools.
📦 Mock es modules using [Import Maps](./writing-tests/mocking.md).
🔧 Exposes browser properties like viewport size and dark mode.
⏱ Runs tests in parallel and isolation.
👀 Interactive watch mode.
🏃 Fast development by rerunning only changed tests.
🚀 Powered by [esbuild](/docs/dev-server/plugins/esbuild.md) and [rollup plugins](/docs/dev-server/plugins/rollup.md)
See [our website](https://modern-web.dev/docs/test-runner/overview/) for full documentation.
## Installation
Install the web test runner:
```
npm i --save-dev @web/test-runner
```
## Basic commands
Do a single test run:
```
web-test-runner test/**/*.test.js --node-resolve
wtr test/**/*.test.js --node-resolve
```
Run in watch mode, reloading on file changes:
```
web-test-runner test/**/*.test.js --node-resolve --watch
wtr test/**/*.test.js --node-resolve --watch
```
Run with code coverage profiling (this is slower):
```
web-test-runner test/**/*.test.js --node-resolve --coverage
wtr test/**/*.test.js --node-resolve --coverage
```
Transform JS to a compatible syntax based on user agent:
```
web-test-runner test/**/*.test.js --node-resolve --esbuild-target auto
wtr test/**/*.test.js --node-resolve --esbuild-target auto
```
## Guide
Check out this [step by step guide](../../docs/guides/test-runner/getting-started.md) to get started.
## Example projects
Check out the example projects for a fully integrated setup.
## Documentation
See [our website](https://modern-web.dev/docs/test-runner/overview/) for full documentation.