This is fair, but also a tooling or process problem. The co-worker should add the test to a new branch / test it on main. If it fails that's a new ticket (with

This is fair, but also a tooling or process problem. The co-worker should add the test to a new branch / test it on main. If it fails that's a new ticket (with the great side effect of having a failing test). If that passes it's a problem in their branch. If not it's the same as having a broken main which happens anyway and you deal with that as you usually do.