1533464 - [wpt-sync] Sync PR 15658 - Make manifest items lists instead of sets

Status: NEW

(Testing :: web-platform-tests, enhancement, P4)

Description

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

Sync web-platform-tests PR 15658 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/15658
Details from upstream follow.

Sam Sneddon <[e-mail]> wrote:

Make manifest items lists instead of sets

This saves ~0.4s locally when running ./wpt run. Semantically, this is wrong and could potentially cause issue in tests when comparing when items we get, but it does provide a reasonable performance gain through avoiding hashing the items.

Pushing this PR up even though I fundamentally dislike it to at least show what the changes are.

The perf gain comes from two places:

• updating the manifest at the start of the run (and we create all the reftest items then, which we won't have to do assuming https://github.com/web-platform-tests/rfcs/pull/15 passes),
• when loading all manifest items prior to filtering tests to run (which we won't have to do if we're more intelligent about the filtering, which we need to be to get larger perf gains in the specified-test case).

Personally, I'd rather wait for the other two things to fix rather than using the wrong data structure here, despite the perf benefit.