1961064 - Intermittent toolkit/components/extensions/test/xpcshell/test_ext_contentscript_order.js | single tracking bug

Status: RESOLVED FIXED

(WebExtensions :: General, defect, P5)

Description

[Treeherder Bug Filer]

Filed by: chorotan [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer?job_id=504353767&repo=mozilla-central
Full log: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/O5kaTSsHRAOS0eFasDNWXA/runs/0/artifacts/public/logs/live_backing.log

---

task 2025-04-17T01:11:09.597Z] 01:11:09     INFO -  TEST-PASS | uriloader/exthandler/tests/unit/test_punycodeURIs.js | took 1173ms
[task 2025-04-17T01:11:09.606Z] 01:11:09     INFO -  Retrying tests that failed when run in parallel.
[task 2025-04-17T01:11:09.612Z] 01:11:09     INFO -  TEST-START | xpcshell-remote.toml:toolkit/components/extensions/test/xpcshell/test_ext_contentscript_order.js
[task 2025-04-17T01:11:10.621Z] 01:11:10  WARNING -  TEST-UNEXPECTED-FAIL | xpcshell-remote.toml:toolkit/components/extensions/test/xpcshell/test_ext_contentscript_order.js | xpcshell return code: 0
[task 2025-04-17T01:11:10.633Z] 01:11:10     INFO -  TEST-INFO took 1010ms
[task 2025-04-17T01:11:10.633Z] 01:11:10     INFO -  >>>>>>>
[task 2025-04-17T01:11:10.634Z] 01:11:10     INFO -  (xpcshell/head.js) | test MAIN run_test pending (1)
[task 2025-04-17T01:11:10.634Z] 01:11:10     INFO -  (xpcshell/head.js) | test run_next_test 0 pending (2)
[task 2025-04-17T01:11:10.634Z] 01:11:10     INFO -  (xpcshell/head.js) | test MAIN run_test finished (2)
[task 2025-04-17T01:11:10.634Z] 01:11:10     INFO -  running event loop
[task 2025-04-17T01:11:10.634Z] 01:11:10     INFO -  xpcshell-remote.toml:toolkit/components/extensions/test/xpcshell/test_ext_contentscript_order.js | Starting setup check_remote
[task 2025-04-17T01:11:10.635Z] 01:11:10     INFO -  (xpcshell/head.js) | test check_remote pending (2)

Comment 1

[Intermittent Failures Robot]

9 failures were associated with this bug in the last 7 days.

Repository breakdown:

• autoland: 2
• mozilla-central: 5
• try: 2

Table

	msix	no_variant
windows10-64-2009-qr--/opt		6
windows11-32-24h2--/opt		1
windows11-64-24h2--/opt	1	1

For more details, see:

https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=1961064&startday=2025-04-14&endday=2025-04-20&tree=all

Comment 2

[Intermittent Failures Robot]

20 failures were associated with this bug in the last 7 days.

Repository breakdown:

• autoland: 9
• try: 5
• comm-central: 2
• mozilla-central: 4

Table

	no_variant	spi-nw
macosx1470-64--/opt	2	6
macosx1470-64-devedition--/opt	2
windows10-64-2009-qr--/opt	4
windows11-32-24h2--/opt	3
windows11-64-24h2--/opt	3

For more details, see:

https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=1961064&startday=2025-04-21&endday=2025-04-27&tree=all

Comment 3

[Intermittent Failures Robot]

22 failures were associated with this bug in the last 7 days.

Repository breakdown:

• autoland: 6
• mozilla-beta: 10
• try: 3
• mozilla-central: 3

Table

	msix	no_variant	spi-nw
macosx1470-64--/opt		1	4
windows10-64-2009-qr--/opt		10
windows11-32-24h2--/opt		1
windows11-64-24h2-devedition--/opt		3
windows11-64-24h2--/opt	1	2

For more details, see:

https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=1961064&startday=2025-04-28&endday=2025-05-04&tree=all

Comment 4

[Rob Wu [:robwu]]

These failures started immediately after the test landed in bug 1792685.
I looked at recent failures, and the assertion failures (relevant parts pasted below) show that the style sheets are applied in an unexpected order:

From https://searchfox.org/mozilla-central/rev/4bd620c218a01568d541453ce3b215ebf55bca63/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_order.js#374-383 :

TEST-UNEXPECTED-FAIL | xpcshell-remote.toml:toolkit/components/extensions/test/xpcshell/test_ext_contentscript_order.js | test_css_order - [test_css_order : undefined] start_2.css (not cached) applies before frame.onload - "1" == "2"
TEST-UNEXPECTED-FAIL | xpcshell-remote.toml:toolkit/components/extensions/test/xpcshell/test_ext_contentscript_order.js | test_css_order - [test_css_order : undefined] start_3.css (cached, blocked on start_2.css) applies before frame.onload - "2" == "3"

This shows something interesting:

• The first assertion failure implies that the --css-start-12 variable from start_1.css was applied (value "1") instead of value "2" expected from start_2.css.
• The second assertion failure implies that the --css-start-23 variable from start_2.css was applied (value "2") instead of value "3" expected from start_3.css.
• We expect the styles to apply in the order of start_1.css, start_2.css, start_3.css. With just the first assertion error, one may think that start_2.css did not apply, but the second assertion shows that it did. Therefore the conclusion is that the styles from start_1.css unexpectedly applied after start_2.css (instead of before).
  • The logs also suggest that start_3.css did either not apply, or applied before start_2.css (instead of after). There is not enough information to tell which of the two is the case.
• I reproduced the issue locally, and with additional logging I can confirm that the scripts and styles are scheduled as expected. The issue is likely somewhere between AddSheet and/or getComputedStyle(...).getPropertyValue(...).

There are additional test failures (later) after the initial one, which show the same (incorrect) values.

From https://searchfox.org/mozilla-central/rev/4bd620c218a01568d541453ce3b215ebf55bca63/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_order.js#307 :

TEST-UNEXPECTED-FAIL | xpcshell-remote.toml:toolkit/components/extensions/test/xpcshell/test_ext_contentscript_order.js | test_css_order - [test_css_order : 145] Got expected css order: --css-start-12 should be 2 - Expected: 2, Actual: 1 - false == true

From https://searchfox.org/mozilla-central/rev/4bd620c218a01568d541453ce3b215ebf55bca63/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_order.js#308 :

TEST-UNEXPECTED-FAIL | xpcshell-remote.toml:toolkit/components/extensions/test/xpcshell/test_ext_contentscript_order.js | test_css_order - [test_css_order : 145] Got expected css order: --css-start-23 should be 3 - Expected: 3, Actual: 2 - false == true

Comment 5

[Rob Wu [:robwu]]

I can reproduce the issue locally, but only on a release build, not on a debug build.

When addSheet is used and mStyleSetFilled is true in Document::AddAdditionalStyleSheet, then the stylesheets are appended in the expected order.

When mStyleSetFilled is false, it is populated later via Document::FillStyleSet, in Document::FillStyleSetDocumentSheets. The AppendSheetsToStyleSet method appends the stylesheet in the reverse order. Consequently, the order of stylesheets is start_3.css, start_2.css, start_1.css instead of the expected start_1.css, start_2.css, start_3.css.

When I fix the order to be non-reversed, the failure goes away. I'll attach a patch.

Comment 6

[Rob Wu [:robwu]]

Attachment: Bug 1961064 - Fix order of windowUtils.addSheet

See https://bugzilla.mozilla.org/show_bug.cgi?id=1961064#c5

Comment 7

[Intermittent Failures Robot]

37 failures were associated with this bug in the last 7 days.

This failure happened more than 30 times this week! Resolving this bug is a high priority.

Try to resolve this bug as soon as possible. If unresolved for 2 weeks, the affected test(s) may be disabled.

Repository breakdown:

• mozilla-central: 10
• autoland: 2
• mozilla-beta: 21
• try: 4

Table

	debug	msix	no_variant	opt	spi-nw
macosx1470-x86_64/opt			2		3
windows10-x86_64/opt			15
windows11-x86/opt			5
windows11-x86_64/opt		5	7

For more details, see:

https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=1961064&startday=2025-05-05&endday=2025-05-11&tree=all

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/730be97ab77d
Fix order of windowUtils.addSheet r=emilio

Comment 9

[amarc]

https://hg.mozilla.org/mozilla-central/rev/730be97ab77d

Comment 10

[Intermittent Failures Robot]

18 failures were associated with this bug in the last 7 days.

Repository breakdown:

• mozilla-beta: 15
• autoland: 2
• try: 1

Table

	asan	ccov	debug	msix	no_variant	opt	spi-nw	tsan
linux1804-x86_64/opt					1
macosx1015-x86_64/opt					1
macosx1470-x86_64/opt							1
windows10-x86_64/opt					7
windows11-x86_64/opt				2	6

For more details, see:

https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=1961064&startday=2025-05-12&endday=2025-05-18&tree=all

Comment 11

[Intermittent Failures Robot]

6 failures were associated with this bug in the last 7 days.

Repository breakdown:

• mozilla-beta: 2
• mozilla-release: 4

Table

	msix	no_variant
windows10-x86_64/opt		4
windows11-x86_64/opt	1	1

For more details, see:

https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=1961064&startday=2025-05-19&endday=2025-05-25&tree=all

Comment 12

[Intermittent Failures Robot]

3 failures were associated with this bug in the last 7 days.

Repository breakdown:

• mozilla-release: 3

Table

	no_variant	opt
macosx1500-aarch64/opt	1
windows10-x86_64/opt	1
windows11-x86_64/opt	1

For more details, see:

https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=1961064&startday=2025-06-02&endday=2025-06-08&tree=all

Comment 13

[Intermittent Failures Robot]

1 failures were associated with this bug in the last 7 days.

Repository breakdown:

• mozilla-release: 1

Table

	msix
windows11-x86_64/opt	1

For more details, see:

https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=1961064&startday=2025-06-16&endday=2025-06-22&tree=all