./mach wpt --enable-fission testing/web-platform/tests/webdriver/tests/element_click/navigate.py

for example doesn't seem to enable Fission.
On needs to explicitly use
--setpref fission.autostart=true

Hi James, you added the --enable-fission option to mach wpt in bug 1622338. This bug reports --enable-fission doesn't work when running WPT .py tests. Can I assign this bug to you?

Tracking for Fission milestone M6c.

It's because we aren't setting the profile when running wdspec tests. I have another patch that fixes this, but some investigation of failures is required.

Huh, but we correctly pass the preference via the new session command over to geckodriver:
https://treeherder.mozilla.org/logviewer?job_id=323759516&repo=mozilla-central&lineNumber=1481

And all those preferences are getting correctly set in the Firefox profile before it gets started.

Also note that element_click/navigate.py is currently marked as disabled for Fission in the manifest.

Oh, wait. In CI we make use of mozharness instead. Strange that we never noticed that yet.

James, will you work on that bug? If not maybe you can share some code?

I've pinged jgraham separately to get an update on this.
Henrik, do you have any other updates/ideas for fixing this?

Apologies for the lack of update here; I was doing the work but forgot to update the relevant bugs. The problem turned out to be "we don't pass a profile into the wdspec Firefox instances at all" and it required some changes in geckodriver so we could pass in a profile and also set test-specific prefs. Anyway https://phabricator.services.mozilla.com/D101772 is the relevant stack. I think :whimboo is the right reviewer but he's away for a couple of weeks. If there's something urgent blocked on this then we could figure out a different review setup.

Apologies again for the radio silence.

Thank you, jgraham. This is needed to unblock devs working on Fission WPTs, but does not need to block M6c or M7 (Fission on Beta) so moving this to M8.
Keeping whimboo's NI here so they can address jgraham's patch when they're back.

(In reply to James Graham [:jgraham] from comment #7)

Apologies for the lack of update here; I was doing the work but forgot to update the relevant bugs. The problem turned out to be "we don't pass a profile into the wdspec Firefox instances at all" and it required some changes in geckodriver so we could pass in a profile and also set test-specific prefs. Anyway https://phabricator.services.mozilla.com/D101772 is the relevant stack. I think :whimboo is the right reviewer but he's away for a couple of weeks. If there's something urgent blocked on this then we could figure out a different review setup.

Hi James, what are the next steps for this bug (and --enable-webrender bug 1678044 and profile bug 1686707 blocking it)? Looks like :whimboo left some review feedback for bug 1686707's patch:

https://phabricator.services.mozilla.com/D101772#3461853

Tentatively assigning to jgraham because he is assigned to bug 1678044 and bug 1686707 blocking this bug.

Patches are updated and just waiting for re-review. Sorry for the long delay here.

James, what's left for this particular bug?

I believe this should be fixed, unless we missed wiring up the fission-specific part of the patch.

(In reply to Chris Peterson [:cpeterson] from comment #10)

Tentatively assigning to jgraham because he is assigned to bug 1678044 and bug 1686707 blocking this bug.

(In reply to James Graham [:jgraham] from comment #13)

I believe this should be fixed, unless we missed wiring up the fission-specific part of the patch.

Thanks for confirming. In that case, I'll close this bug as fixed (by bug 1678044 and/or bug 1686707).

I just checked with the argument and it indeed correctly enables Fission.