We created the first browser tests in client/data-bridge/tests/selenium (starting https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Wikibase/+/523863)
They do not run as part of regular CI however.
This might be easier / possible in a more elegant fashion following T199116: Quibble should run `npm install` and `npm run selenium-test` for each extension/skin that has Selenium tests
Notes
- comparable change mending wikibase config for termbox CI