In the WPT PR 41665 [1],
preload-csp.sub.html was added connect-src:'none' in the CSP [2],
the reason is that the json modules will use 'connect-src' as the CSP
directive, see the destination "json" in [3].
However, this test calls "hasArrivedAtServer" to verify the result [4],
which uses 'fetch()' API. [5]
And according the CSP spec, the directive for fetch() is "connect-src" (See
the empty string in [3])
Hence the change introduced in [2] causes the call to fetch() will
violate the CSP restriction, and causes the test failed on all browser
vendors. [6]
Further check the history on the wpt.fyi in [6], we can find out all
browsers started to fail since Oct.31.2023, which is also the date the
PR 41665 [1] is merged into master [7].
Now back to the test itself, since preloading json modules is not
allowed in previous patch D234849 [8] and whatwg PR 10212 [9], we can
just simply remove the connect-src: 'none' CSP directive.
[1]: https://github.com/web-platform-tests/wpt/pull/41665
[2]: https://github.com/web-platform-tests/wpt/commit/40db1c8a3564f78156416334898f2a6914dd6de9#diff-18344ffd5be3dce2faabd52b30c10d3c7beeef3a024eac638c8e0e71b07bb7c6R2
[3]: https://w3c.github.io/webappsec-csp/#effective-directive-for-a-request
[4]: https://github.com/web-platform-tests/wpt/blob/803b53367671fef86957c611a38e1d145044a97c/preload/preload-csp.sub.html#L33
[5]: https://github.com/web-platform-tests/wpt/blob/803b53367671fef86957c611a38e1d145044a97c/preload/resources/preload_helper.js#L10
[6]: https://wpt.fyi/results/preload/preload-csp.sub.html?label=experimental&label=master&aligned
[7]: https://github.com/web-platform-tests/wpt/commit/40db1c8a3564f78156416334898f2a6914dd6de9
[8]: https://phabricator.services.mozilla.com/D234849
[9]: https://github.com/whatwg/html/pull/10212