1556881 - Don't assume the dom.storage.next_gen pref is live

Status: RESOLVED FIXED

(Core :: Privacy: Anti-Tracking, enhancement, P3)

Description

[(no longer active)]

Here: https://searchfox.org/mozilla-central/rev/9eb2f739c165b4e294929f7b99fbb4d90f8a396b/dom/localstorage/LocalStorageCommon.cpp#41 we read the value of the pref at startup only once and never update it again. This affects e.g. what window.localStorage returns.

However we have tests in the tree like https://searchfox.org/mozilla-central/rev/9eb2f739c165b4e294929f7b99fbb4d90f8a396b/toolkit/components/antitracking/test/browser/browser_partitionedLocalStorage_events.js#67 which are written as if dom.storage.next_gen were a live pref!

Is this pref not being live intentional? Can we convert it into a live pref so that these tests actually test the thing they think they are testing rather than a combination of the new/old LS backends?

Comment 1

[Jan Varga [:janv]]

It's intentional. It would be really hard to make it a live pref.

Comment 2

[(no longer active)]

Interesting! So attempting to set this pref inside a browser-chrome test is completely broken, right? I see inside the debugger that the code is instantiating the old LS backend while the test is thinking the new backend is being tested...

Comment 3

[Andrew Sutherland [:asuth] (he/him)]

I was thinking we might be able to make it work via nsIQuotaManagerService::Reset()

Comment 4

[Andrea Marchesini [:baku]]

Andrew, do you have time to work on it?

Comment 5

[(no longer active)]

We talked about this at the all hands and decided to morph the bug into fixing our test to not assume the pref is live.

Comment 6

[(no longer active)]

Attachment: Bug 1556881 - Fix browser_partitionedLocalStorage_events.js to not assume the dom.storage.next_gen pref is live;

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/1d89c2f4521b
Fix browser_partitionedLocalStorage_events.js to not assume the dom.storage.next_gen pref is live; r=baku

Comment 8

[Daniel Varga [:dvarga]]

https://hg.mozilla.org/mozilla-central/rev/1d89c2f4521b