[chrisjsewell]

What and why

MyST-Parser master (723cffc, the coming 5.2.0) reworks heading anchors (executablebooks/MyST-Parser#1158):
for a heading with an explicit (target)=, the target becomes the section's first (primary) id.
That breaks three sphinx-design tests, although sphinx-design's own output is unchanged:

• test_snippets.py::test_snippets_myst[html-card-link] and test_snippets_myst_post[html-card-link]:
  the section's ids flip from clickable-cards cards-clickable to cards-clickable clickable-cards.
  The RST and MyST snippets share one fixture, and docutils keeps the old order, so no single fixture fits both.
• test_badge_tooltips.py::test_ref_badge_tooltip_survives_resolution[html-myst]:
  it counted every href="#my-target" in the page (4 != 2),
  because the theme's headerlink and sidebar TOC now also point at #my-target.

This PR changes tests only:

1. Badge test: count only the anchors with the sd-badge class that link to #my-target, which is what the assertion is about.
2. Snippet tests: sort each element's ids before serialising, in all four snippet tests (RST and MyST, pre and post transforms),
   and regenerate the two card-link fixtures. One line changes in each. The full set of ids is still compared; only their order is ignored.

No other fixture changes. Landing this before the MyST-Parser 5.2.0 tag keeps sphinx-design's CI green when 5.2.0 is released
(the testing extra allows myst-parser>=4,<6).

How it was tested

Python 3.13, Sphinx 9.2.0, with pytest tests:

Environment	main (before)	This branch
myst-parser 5.1.0 from PyPI, docutils 0.22.4	272 passed, 1 skipped	272 passed, 1 skipped
myst-parser master 723cffc (git+https://github.com/executablebooks/MyST-Parser@master), docutils 0.23	3 failed, 269 passed, 1 skipped	272 passed, 1 skipped
testing-no-myst (Python 3.11, Sphinx 9.0.4)	not run	182 passed, 91 skipped

The 5.1.0 environment was checked to be the real release (its metadata requires docutils<0.23; master's __version__ is also 5.1.0).

The sorting is needed. With it disabled and the new fixtures kept, tests/test_snippets.py fails on both versions:
on 5.1.0 all four card-link tests fail (2 RST, 2 MyST), and on master the 2 RST card-link tests fail.

pre-commit run --all-files passes.

Notes for the reviewer

• sort_ids is a local helper in tests/test_snippets.py.
  It is deliberately not part of the semi-public sphinx_design.testing.normalize_doctree_xml,
  so downstream extensions that use that helper do not get churn in their own fixtures.
• Add link-new-tab flag to card / grid-item-card directives #298 adds a card to the card-link snippets, so its card-link fixtures must be regenerated.
  Doing that on top of this PR records sorted ids, which do not depend on the MyST version.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.63%. Comparing base (4f66f32) to head (49a1929).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #310   +/-   ##
=======================================
  Coverage   92.63%   92.63%           
=======================================
  Files          13       13           
  Lines        1371     1371           
=======================================
  Hits         1270     1270           
  Misses        101      101           

Flag	Coverage Δ
pytests	92.63% <ø> (ø)

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