Updating the URL would be nice but might be "interesting" for tests that depend on the current URL - hopefully we can update "just" a few helpers and that'll be enough.

As per guidance from Vicky, for tracking, we're marking all the bugs that people are working on as P1.

(In reply to :Gijs (he/him) from comment #0)

Updating the URL would be nice but might be "interesting" for tests that depend on the current URL - hopefully we can update "just" a few helpers and that'll be enough.

Does the ability to redirect from about:preferences to about:settings exist?

(In reply to Romain Testard [:RT] from comment #3)

(In reply to :Gijs (he/him) from comment #0)

Updating the URL would be nice but might be "interesting" for tests that depend on the current URL - hopefully we can update "just" a few helpers and that'll be enough.

Does the ability to redirect from about:preferences to about:settings exist?

Not without work, but that wouldn't fix the tests problem anyway as they wait for about:preferences to load (which it wouldn't anymore). I ended up not including this in my patch here.

Marking as P2. Per experience review we agreed to mark as P1 bugs only bugs that will block MR1.

(In reply to Romain Testard [:RT] from comment #3)

(In reply to :Gijs (he/him) from comment #0)

Updating the URL would be nice but might be "interesting" for tests that depend on the current URL - hopefully we can update "just" a few helpers and that'll be enough.

Does the ability to redirect from about:preferences to about:settings exist?

I wrote up a more detailed answer to this in https://bugzilla.mozilla.org/show_bug.cgi?id=1697522#c2 . TL;DR: It's not straightforward and I'm not going to do it in this bug, and it might not make 89.

Backed out for failures on browser_experimental_features.js

backout: https://hg.mozilla.org/integration/autoland/rev/a76440dd439418b81727d18a3b722c263fe9c0b1

push: https://treeherder.mozilla.org/jobs?repo=autoland&selectedTaskRun=AroBtq6vQBm0oQIcyJMlaQ.0&group_state=expanded&revision=816285ac4de4c0cd590144c697c2c37f5973ed91&searchStr=browser-chrome

failure log: https://treeherder.mozilla.org/logviewer?job_id=334276687&repo=autoland&lineNumber=16424

[task 2021-03-24T12:17:49.298Z] 12:17:49 INFO - TEST-PASS | browser/components/preferences/tests/browser_experimental_features.js | The category is not hidden -
[task 2021-03-24T12:17:49.298Z] 12:17:49 INFO - Buffered messages logged at 12:16:24
[task 2021-03-24T12:17:49.298Z] 12:17:49 INFO - Console message: [JavaScript Error: "uncaught exception: [fluent] Missing translations in en-US: containers-preferences-button."]
[task 2021-03-24T12:17:49.299Z] 12:17:49 INFO - Buffered messages finished
[task 2021-03-24T12:17:49.299Z] 12:17:49 INFO - TEST-UNEXPECTED-FAIL | browser/components/preferences/tests/browser_experimental_features.js | Test timed out -
[task 2021-03-24T12:17:49.303Z] 12:17:49 INFO - Not taking screenshot here: see the one that was previously logged
[task 2021-03-24T12:17:49.303Z] 12:17:49 INFO - TEST-UNEXPECTED-FAIL | browser/components/preferences/tests/browser_experimental_features.js | A promise chain failed to handle a rejection: [fluent] Missing translations in en-US: containers-preferences-button. - stack: (No stack available.)
[task 2021-03-24T12:17:49.303Z] 12:17:49 INFO - Rejection date: Wed Mar 24 2021 12:16:24 GMT+0000 (Greenwich Mean Time) - false == true - JS frame :: resource://testing-common/PromiseTestUtils.jsm :: assertNoUncaughtRejections :: line 285
[task 2021-03-24T12:17:49.304Z] 12:17:49 INFO - Stack trace:
[task 2021-03-24T12:17:49.304Z] 12:17:49 INFO - resource://testing-common/PromiseTestUtils.jsm:assertNoUncaughtRejections:285
[task 2021-03-24T12:17:49.304Z] 12:17:49 INFO - chrome://mochikit/content/browser-test.js:nextTest:631
[task 2021-03-24T12:17:49.304Z] 12:17:49 INFO - chrome://mochikit/content/browser-test.js:timeoutFn:1222
[task 2021-03-24T12:17:49.304Z] 12:17:49 INFO - GECKO(1656) | MEMORY STAT | vsize 8183MB | residentFast 639MB | heapAllocated 132MB
[task 2021-03-24T12:17:49.304Z] 12:17:49 INFO - TEST-OK | browser/components/preferences/tests/browser_experimental_features.js | took 90117ms

https://hg.mozilla.org/mozilla-central/rev/34d922440886