test: align RST fixtures with auto_id_prefix to fix docutils 0.18 CI failures

[zkoppert]

Why

CI has been red on master and on every open PR (for example the Dependabot bump in #2086). Three reStructuredText tests fail: test_rst, test_long.rst, and test_toc.rst.

The root cause traces back to #2081 ("Fix id names in rst renders after docutils 0.18"). That PR set auto_id_prefix: 'id' in lib/github/commands/rest2html to keep the pre-docutils-0.18 table-of-contents anchor scheme (id1, id2, ... idN). The renderer now emits idN as intended, but the committed fixtures were left holding the docutils-0.18 default (toc-entry-1, toc-entry-2, ...). The rendered output never matched the fixtures, so the tests failed on the #2081 merge run and have stayed red ever since.

The old fixtures were also internally broken: RST section headers carry back-references like <a href="#id1">, but the matching TOC anchors were id="toc-entry-1", so those in-page links pointed at anchors that did not exist.

What changed

I regenerated the three affected fixtures (test/markups/README.rst.html, README.long.rst.html, README.toc.rst.html) against the CI-pinned docutils==0.22.4, so they now carry the idN anchors that the existing auto_id_prefix: 'id' setting actually produces. No source code changed; the diff is only the id attribute values on TOC-entry <a> tags, and it repairs the dangling in-page anchors as a side effect.

I chose to complete #2081's approach rather than the alternatives. Loosening the assert_html_equal harness to ignore id differences would mask real drift, and reverting auto_id_prefix would undo the deliberate choice to keep stable idN anchors.

	Before	After
TOC anchor ids	id="toc-entry-1"	id="id1"
In-page back-refs (href="#id1")	dangling	resolve
RST tests (docutils 0.22.4)	3 failures	0 failures

Testing

I reproduced the failure locally with the CI-pinned docutils==0.22.4, regenerated the fixtures with UPDATE=1, and confirmed the full suite passes:

62 runs, 137 assertions, 0 failures, 0 errors, 0 skips
Line Coverage: 100.0% (226 / 226)

I also verified the diff changes nothing but id values: after normalizing every id="..." token to a placeholder, the before and after fixtures are byte-identical. A three-model review (Opus, Sonnet, GPT-5.5) independently confirmed the scope, the id uniqueness, and that the regenerated output matches docutils 0.22.4 exactly.

Rollout

Low risk: the change is test-fixture only, gated behind CI across Ruby 3.3, 3.4, and 4.0. If a future docutils pin bump shifts the global auto-id counter (the long fixture uses id113–id138), the fixtures will need regenerating again with UPDATE=1 bundle exec rake. Rollback is a straight revert.

[Copilot]

Pull request overview

Updates reStructuredText HTML fixtures so their generated TOC entry id attributes match the renderer’s auto_id_prefix: 'id' behavior (restoring the pre-docutils-0.18 idN scheme) and fixing the currently failing RST-related tests under the CI-pinned docutils version.

Changes:

• Regenerates RST HTML fixtures to replace id="toc-entry-N" with id="idN" in TOC entry links.
• Aligns TOC ids with existing in-page back-references (href="#idN") so intra-page links resolve correctly.
• Removes all remaining toc-entry-* ids from the affected fixtures.

Show a summary per file

File	Description
test/markups/README.rst.html	Updates TOC entry ids from toc-entry-* to id* to match the renderer output.
test/markups/README.toc.rst.html	Updates nested TOC entry ids to id1/id2/id3 to match generated anchors.
test/markups/README.long.rst.html	Updates long TOC entry ids to the generated id113–id138 sequence for docutils 0.22.4 output parity.

Review details

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• Files reviewed: 3/3 changed files
• Comments generated: 0
• Review effort level: Low