[random test failure] ToolbarActiveTrail::testToolbarActiveTrail

Had a brief look. The test waits for a menu link to be visible, then checks if a grandparent element has a class. The class menu-item--active-trail is added by toolbar.menu.js, so it's feasible that the element is visible before the class has been added. I'd probably try updating the test to use \Drupal\FunctionalJavascriptTests\JSWebAssert::waitForHelper to test the link is visible AND the grandparent has the class.

Great idea with combining the selectors!

That's passed 2 runs of 100 repeats. Spinning up a clean MR to see how often it fails without the fix.

Another 100 passed with the fix, the base MR has failed 2/200