Frontend & browser·Testing a user interface
a real browser ran the tests with no window on screen, on a machine with no display at all.
Headless browser
Also calledheadless Chrome
A real browser engine driven programmatically without a visible window, which is what makes end-to-end tests runnable in CI. It gives real layout, real CSS and real timing, unlike a simulated DOM. Small differences between headless and headed mode still exist — fonts, media codecs, some GPU paths — so a failure in one mode and not the other is worth taking seriously rather than dismissing.