1842714 - [wpt-sync] Sync PR 40961 - Rework skew-test1.html to have more reliable expectations.

Status: RESOLVED FIXED

(Core :: Web Painting, task, P4)

Description

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Sync web-platform-tests PR 40961 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/40961
Details from upstream follow.

Daniel Holbert <[e-mail]> wrote:

Rework skew-test1.html to have more reliable expectations.

The old version of this test produced a polygon without precisely-representable vertices, which turned out to be problematic. The reference case might have been correct, but all browsers still had fuzzy-failures, and at least two engines (WebKit and Gecko) required fuzzy-tolerances that would allow nearly 1000 pixels to differ by essentially arbitrarily-large amounts in any color channel.

This reworked version of the test uses multiples of 45deg for the skew angles, which produces a diamond shape whose bounding-box is exactly 2x the width of the original square. This exactness makes the test's expectations easier to reason about and validate.

This reworked version of the test also uses the common "covered-up-target" test approach, to ensure that the transformed shape is the correct size, shape, and position, without suffering from fuzzy-failures that arise from antialiasing or pixel-snapping variability.

This implements my proposal in
https://github.com/web-platform-tests/interop/issues/378

Comment 1

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Pushed to try (stability) https://treeherder.mozilla.org/#/jobs?repo=try&revision=813d7a3d8e5ac3d5a64bfa202997213813cc1227

Comment 2

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Test result changes from PR not available.

Comment 3

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Test result changes from PR not available.

Comment 4

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Test result changes from PR not available.

Comment 5

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Test result changes from PR not available.

Comment 6

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Test result changes from PR not available.

Comment 7

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Test result changes from PR not available.

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/8e5380f3a779
[wpt PR 40961] - Rework skew-test1.html to have more reliable expectations., a=testonly
https://hg.mozilla.org/integration/autoland/rev/828bb86138df
[wpt PR 40961] - Update wpt metadata, a=testonly

Comment 9

[Iulian Moraru]

https://hg.mozilla.org/mozilla-central/rev/8e5380f3a779
https://hg.mozilla.org/mozilla-central/rev/828bb86138df