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Headless Chrome

TestivAI captures whatever browser your tests drive, headless or not. Headless is the usual setup for CI and servers: no display, no window manager, and nothing to install beyond the browser itself.

Keep capture conditions identical​

A baseline only means something against captures taken the same way. Between the run that approved a baseline and every run that compares against it, keep these the same:

  • Browser and version. Pin it (lockfile, Docker image tag). See Docker.
  • Headless or headed. Don't approve from a headed local run and compare in headless CI.
  • Viewport size. Headless Chrome's default window is small (780×580 in Chrome 141) and is not guaranteed to stay the same between versions, so set the size explicitly.
  • OS and fonts. See cross-platform baselines.

Per framework​

Playwright runs headless by default. The viewport comes from your project config (use: { viewport: { width: 1280, height: 800 } }) or a device profile for mobile web.

Selenium needs headless and the window size set on the driver:

const options = new chrome.Options().addArguments('--headless=new', '--window-size=1280,800');
options = webdriver.ChromeOptions()
options.add_argument("--headless=new")
options.add_argument("--window-size=1280,800")

The Selenium guide covers which browsers capture the full page and which capture the viewport.

WebdriverIO takes the same Chrome arguments in its capabilities:

capabilities: [{
  browserName: 'chrome',
  'goog:chromeOptions': { args: ['--headless=new', '--window-size=1280,800'] },
}],

No test suite: standalone mode is headless​

npx testivai witness <url> launches its own headless Chrome (--headless=new, scrollbars hidden) at a 1280×800 viewport. Change the size with --viewport 1440x900 or viewport in .testivai/config.json. See testivai witness for the flags, and Docker for the environment variables that pick the binary and control the sandbox.

To capture from a Chrome you started yourself, start it with a debugging port and pass the same port:

google-chrome --headless=new --remote-debugging-port=9222 &
npx testivai witness http://localhost:3000 --port 9222