W3C Webdriver conquering automation of Shadow DOM

query-selector-shadow-dom

querySelector that can pierce Shadow DOM roots without knowing the path through nested shadow roots. Useful for automated testing of Web Components. Production use is not advised, this is for test environments/tools such as Web Driver, Playwright, Puppeteer

Developing Components: Testing

Using @web/test-runner for testing web components in a real browser

Testing Shadow DOM elements in Selenium

In Selenium 4, there is now a way to access Shadow DOM nodes

Open Web Components: Testing

Opinionated package that combines and configures testing libraries