[D7 PHP 8.3] TextSummaryTestCase::testLength() fails on some libxml versions

Drupal 10.2 solved the issue via 🐛 Upgrade filter system to HTML5 Fixed

probably it needs some wrapper which is checking for libxml version or relax test somehow

An answer from libxml2 team is that this was a deliberate change, so we need to find workaround as @andypost mentioned.

See: https://gitlab.gnome.org/GNOME/libxml2/-/issues/615

Looks like checking for libxml version in test looks the most viable solution

Yes, we can fix the test, but I am not sure if this change in libxml2 could not have a potential impact on the real core functionality in some edge cases (and that we will not hide some problems when we use this workaround). Other than that, I am not sure how many different "characters" are affected by this change - so far we know that parsing < is problematic, but there can be more I think.

There's been 15 releases of libxml2 since 2.9.14
any chance that this issue is fixed in https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.12.3 v2.12.3?

We can try it, but I do not think so, because when I raised this question here: https://gitlab.gnome.org/GNOME/libxml2/-/issues/615, the answer was it is not a bug, but a deliberate change in the library.

ah ok, ya so the new versions would likely not have changed from the 2.9.14
Funny they couldn't make it work for both html4 and html5

There's bigger changes are coming in Dom PHP extension https://wiki.php.net/rfc/opt_in_dom_spec_compliance

We discussed this issue with @Fabianx on Slack and we agreed it would be the best to just skip the testing of this edge-case for the LIBXML version >= 2.9.14. It seems like the change in libxml2 have not caused other issues with D7, as other tests are not failing.

I have created a MR here with the proposed fix (it just skips the testing of "<" when tested with filter_htmlcorrector in case the LIBXML version is >= 2.9.14. It was possible to do this in several ways, but I think this approach has the smallest impact (unfortunatelly it seems not easily possible to remove the array element entirely, as the for loop is testing the lenght by array key position).

All current tests seems to be green with this change: https://git.drupalcode.org/project/drupal/-/pipelines/170137 . Also the PHP 8.3 test is without this failure (only the session one is still present after applying the fix from there): https://www.drupal.org/pift-ci-job/2893113 → .

For illustration, if we combine fix from this issue and fix from the other one (session failure), the 8.3 testing is green: https://git.drupalcode.org/project/drupal/-/pipelines/170105 (see the META issue).

Moving to Needs review.

100% green here for 8028