1703074 - overflow-auto-005.html fails (on platforms with non-overlay scrollbars) due to the test mistakenly assuming scrollbars will always be on the same side regardless of writing-mode

Status: RESOLVED DUPLICATE of bug 1706220

(Core :: Layout: Flexbox, task)

Description

[Daniel Holbert [:dholbert]]

This test fails in Firefox right now (at least on Linux and Windows), due to a mistaken assumption in the test:
https://wpt.fyi/results/css/css-flexbox/overflow-auto-005.html

Testcase: https://wpt.live/css/css-flexbox/overflow-auto-005.html
Reference case: https://wpt.live/css/css-flexbox/reference/overflow-auto-005-ref.html

The test is implicitly assuming that scrollbars are always on the same side of the scrollable element, regardless of its writing-mode, but that's not how Firefox does things; we place the scrollbars on the logical "end" side. This means the vertical scrollbar is on the left side of the vertical-rl elements in the second row of the testcase. Whereas in the reference case, there's no custom writing-modes, so the scrollable elements always have the scrollbar on the default side (bottom & right).

The test needs fixing to avoid making this unwarranted assumption about scrollbar right-side-placement.

This test is part of the compat2021 test set (it's listed in https://github.com/Ecosystem-Infra/wpt-results-analysis/blob/main/compat-2021/css-flexbox-tests.txt ); hence, marking as blocking the compat2021 metabug.

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: testcase showing that Chrome is inconsistent about scrollbar placement

Actually, it looks like Chrome places the scrollbar on the logical "end" side as well for the inline axis, but not for the block axis.

I had an idea for a trivial fix to the WPT -- just adding direction:rtl to the elements in the reference case (to flip the scrollbar side there), which nearly makes the test valid -- but that makes the test fail in Chrome due to this inconsistency.

I'll file a Chrome bug on that inconsistency. In the meantime, this test should be removed from the compat2021 test set since it has this unjustified expectation about vertical-rl scrollbars being placed on the right side.

foolip, what's the correct process for removing tests from the test set? Should I make a pull request to https://github.com/Ecosystem-Infra/wpt-results-analysis to comment out the test?

Comment 2

[Daniel Holbert [:dholbert]]

(In reply to Daniel Holbert [:dholbert] from comment #1)

Actually, it looks like Chrome places the scrollbar on the logical "end" side as well for the inline axis, but not for the block axis.

I filed https://bugs.chromium.org/p/chromium/issues/detail?id=1195933 on this inconsistency, FWIW.

Comment 3

[Daniel Holbert [:dholbert]]

(See also bug 1625674 comment 4 where I previously ran into this when the test was originally added to the WPT testsuite, under its original name flexbox-overflow-auto-001.html. Looks like there I had an open needinfo on the test author over there, which probably fell off their radar.)

Comment 4

[Daniel Holbert [:dholbert]]

(In reply to Daniel Holbert [:dholbert] from comment #2)

(In reply to Daniel Holbert [:dholbert] from comment #1)

Actually, it looks like Chrome places the scrollbar on the logical "end" side as well for the inline axis, but not for the block axis.

I filed https://bugs.chromium.org/p/chromium/issues/detail?id=1195933 on this inconsistency, FWIW.

...and I filed https://bugs.webkit.org/show_bug.cgi?id=224224 on this in WebKit.

Comment 5

[Daniel Holbert [:dholbert]]

Looks like David Grogan is fixing this test in https://github.com/web-platform-tests/wpt/pull/28591. Should be able to close this once that's merged.

Comment 6

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

The upstream fix has been imported into gecko in bug 1706220. Let's close this.