They're racy in that they assume that nothing enumerates the window before they've set their prefs, for example. This is blocking other tests (e.g. bug 1255692) from landing because minor timing changes will make the u2f tests fail. They're also using SpecialPowers to directly set their prefs and leaving them in random states (not to mention not really being e10s-friendly) after the test, instead of using pushPrefEnv like tests are supposed to.

See bug 1255692 comment 5 for the sorts of problems this causes. Basically, right now these tests are preventing any worker tests from being added to the tree.

Comment on attachment 8729542 [details] [diff] [review] u2f.patch Please have someone from bug 1231681 review this; I have too many other things on my plate right now, sorry.

If this can't land in a very short time and we don't have 100% confidence that it will fix the issues observed in the dependencies, but 1231681 needs to be backed out ASAP.

Comment on attachment 8729542 [details] [diff] [review] u2f.patch Review of attachment 8729542 [details] [diff] [review]: ----------------------------------------------------------------- Everything looks like the tests are still good. I'm sorry I didn't know about the Push/Pop pref handling a month ago!

Thanks for the quick fix guys!

Yes, thank you!