I want the ability to send real tab signals during automated testing

For accessibility, all interactive elements must be focusable, in a logical tab order, and not create focus traps. It's impossible to create an automated test for this because the browser, even with flags and permissions, will not send actual Tab commands. So we can’t test whether

• the current focus target receives focusout/blur events or triggers any JS handlers,
• the next focus target in tab sequence receives focus(in) events and triggers any JS handlers,
• document.activeElement is updated, or
• :focus, :focus-within styles get triggered.

Currently, this means testing must be manual. It's time-consuming and requires training if you want to be thorough. Also, certain things you want to do during this test—like test the contrast ratio of the focus styles—is tricky or impossible, even with training because once DevTools get focus, you've ruined your tab order test and document.activeElement style.

If we had this, we could create automated keyboard tests that run fast and produce accurate results. This would increase the awareness of common accessibility problems. Hopefully, over time this would help keyboard users and screen reader users.