1878324 - Puppeteer screenshot tests are failing because of invalid usage of "-webkit-scrollbar"

Status: RESOLVED FIXED

(Remote Protocol :: WebDriver BiDi, defect, P2)

Description

[Henrik Skupin [:whimboo][⌚️UTC+2]]

Several Puppeteer tests are currently failing because in Firefox a vertical scrollbar is displayed which reduces the clientWidth of the content document, and causing grid elements to reflow earlier to the next line. This produces different screenshot data.

Here an example:
https://github.com/puppeteer/puppeteer/blob/6514accb26c785fe3f14d0280de375ce76556493/test/src/screenshot.spec.ts#L90-L99

Comment 1

[Henrik Skupin [:whimboo][⌚️UTC+2]]

The problem here actually is that the loaded HTML test pages use the ::-webkit-scrollbar CSS pseudo element to disable scrollbars, which is not compatible with Firefox. Switching this to scrollbar-width: none for the body and html element works in both Firefox and Chrome (where it is brand-new in the 121 release).

I'll go ahead and prepare a Puppeteer upstream PR.

Also we should get tests added to wdspec which check for the right viewport size when scrollbars are shown or not.

Comment 2

[Henrik Skupin [:whimboo][⌚️UTC+2]]

The upstream Puppeteer PR is: https://github.com/puppeteer/puppeteer/pull/11825

Comment 3

[Henrik Skupin [:whimboo][⌚️UTC+2]]

These are P2 test failures for Puppeteer.

Comment 4

[Henrik Skupin [:whimboo][⌚️UTC+2]]

Actually the creation of new wdspec tests will be covered by bug 1878070. This bug will be kept solely for the Puppeteer fix.

Comment 5

[Henrik Skupin [:whimboo][⌚️UTC+2]]

Attachment: Bug 1878324 - [puppeteer] replace usages of webkit-scrollbar with scrollbar-width

To continue investigating issues with screenshots these
changes will be pulled before the next vendoring.

Comment 6

[Henrik Skupin [:whimboo][⌚️UTC+2]]

The PR got merged upstream. Lets already apply it on mozilla-central so that we can go ahead with further investigations around viewport and screenshots.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/16b81378369b
[puppeteer] replace usages of webkit-scrollbar with scrollbar-width r=webdriver-reviewers,Sasha

Comment 8

[Iulian Moraru]

https://hg.mozilla.org/mozilla-central/rev/16b81378369b