1692122 - Experimental preferences need to define a default-value else they will be disabled by default

Status: RESOLVED FIXED

(Firefox :: Settings UI, defect, P3)

Description

[Jared Wein [:jaws] (please needinfo? me)]

In Features.toml, it is optional for a feature to have a default-value. When one is not specified, false will be used as the default. This obviously will create problems when a pref should be enabled by default. This was brought to my attention after a feature that was initially in the experimental preferences section became enabled by default but users were still getting it disabled since default-value was not specified.

We should explicitly define default-value for all features, and include an automated test that confirms that the default-value specified for the FeatureGate matches the default value in prefs.

Comment 1

[Jared Wein [:jaws] (please needinfo? me)]

Bernard, could you work on this next?

Comment 2

[Jared Wein [:jaws] (please needinfo? me)]

And we should have a separate patch that runs a migration to clear the user pref for "layout.css.focus-visible.enabled" since this pref is the one that has been reported where users were having it disabled on release unintentionally.

[Tracking Requested - why for this release]: We should get at least this separate patch uplifted to beta so users upgrading to 86 have this fixed. This specific pref is removed in 87.

Comment 3

[Emilio Cobos Álvarez (:emilio)]

We should probably do the same for network.preload, whose default also changed.

Comment 4

[Pascal Chevrel:pascalc (PTO until April 26)]

I don't think it needs tracking for 86, we are in RC week, it's unlikely to be landed and uplifted in time for our release candidate.

Comment 5

[Bernard Igiri]

Attachment: Bug 1692122 - Add test to verify that experimental preferences have a default value r=jaws,gijs

Added a test verifying that all experimental preferences have a default value.

Updated all experimental preferences to have a default value.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/733dbe23f125
Add test to verify that experimental preferences have a default value r=Gijs

Comment 7

[Sandor Molnar[:smolnar]]

Backed out for causing xpc failures in test_FeatureGate

Backout link: https://hg.mozilla.org/integration/autoland/rev/f76a59412cba9f21e3f06c661d8b36787d177e95

Push with failures

Failure log

INFO - TEST-START | toolkit/components/featuregates/test/unit/test_FeatureGate.js
[task 2021-03-08T22:18:29.017Z] 22:18:29 WARNING - TEST-UNEXPECTED-FAIL | toolkit/components/featuregates/test/unit/test_FeatureGate.js | xpcshell return code: 0
[task 2021-03-08T22:18:29.018Z] 22:18:29 INFO - TEST-INFO took 555ms
[task 2021-03-08T22:18:29.018Z] 22:18:29 INFO - >>>>>>>
[task 2021-03-08T22:18:29.018Z] 22:18:29 INFO - toolkit/components/featuregates/test/unit/test_FeatureGate.js | xpcw: cd /data/local/tmp/test_root/xpc/toolkit/components/featuregates/test/unit
[task 2021-03-08T22:18:29.019Z] 22:18:29 INFO - toolkit/components/featuregates/test/unit/test_FeatureGate.js | xpcw: xpcshell --greomni /data/local/tmp/test_root/xpcb/geckoview-androidTest.apk -m -e const _HEAD_JS_PATH = "/data/local/tmp/test_root/xpc/head.js"; -e const _MOZINFO_JS_PATH = "/data/local/tmp/test_root/xpc/p/mozinfo.json"; -e const _PREFS_FILE = "/data/local/tmp/test_root/xpc/user.js"; -e const _TESTING_MODULES_DIR = "/data/local/tmp/test_root/xpc/m"; -f /data/local/tmp/test_root/xpc/head.js -e const _HEAD_FILES = ["/data/local/tmp/test_root/xpc/toolkit/components/featuregates/test/unit/head.js"]; -e const _JSDEBUGGER_PORT = 0; -e const _TEST_FILE = ["test_FeatureGate.js"]; -e const _TEST_NAME = "toolkit/components/featuregates/test/unit/test_FeatureGate.js"; -e _execute_test(); quit(0);
[task 2021-03-08T22:18:29.019Z] 22:18:29 INFO - (xpcshell/head.js) | test MAIN run_test pending (1)
[task 2021-03-08T22:18:29.019Z] 22:18:29 INFO - (xpcshell/head.js) | test run_next_test 0 pending (2)
[task 2021-03-08T22:18:29.019Z] 22:18:29 INFO - (xpcshell/head.js) | test MAIN run_test finished (2)
[task 2021-03-08T22:18:29.019Z] 22:18:29 INFO - running event loop
[task 2021-03-08T22:18:29.020Z] 22:18:29 INFO - toolkit/components/featuregates/test/unit/test_FeatureGate.js | Starting testReadAll
[task 2021-03-08T22:18:29.020Z] 22:18:29 INFO - (xpcshell/head.js) | test testReadAll pending (2)
[task 2021-03-08T22:18:29.020Z] 22:18:29 INFO - (xpcshell/head.js) | test run_next_test 0 finished (2

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/cd73f33db8a9
Add test to verify that experimental preferences have a default value r=Gijs

Comment 9

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/cd73f33db8a9

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/comm-central/rev/15fb25b3cae3
Port bug 1692122 - Update feature gate preferences to match Firefox's. rs=bustage-fix DONTBUILD