test(markdown): add regression tests for mixed list markers across blank lines

[jfmcdowell]

Note

This PR was created with AI assistance (Claude Code).

Summary

Closes #9729, closes #9731.

Adds regression tests verifying that mixed ordered delimiters (. vs )) and mixed bullet markers (- vs +) separated by blank lines produce separate lists. The parser already handles this correctly — these tests lock in the behavior.

Test Plan

• just test-crate biome_markdown_parser
• just test-markdown-conformance — 652/652
• just f
• just l

Docs

N/A.

[changeset-bot]

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Latest commit: fb27fa6

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[codspeed-hq]

Merging this PR will not alter performance

✅ 28 untouched benchmarks
⏩ 228 skipped benchmarks¹

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_{Comparing jfmcdowell:fix-md-list-delim-regression-tests (fb27fa6) with main (467fd87)}

Footnotes

1. 228 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 467fd87 and fb27fa6.

📒 Files selected for processing (1)

• crates/biome_markdown_parser/tests/spec_test.rs

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Walkthrough

This PR adds two test cases to validate HTML rendering behaviour for list delimiters across blank lines. Test case 10005 asserts that switching ordered list delimiters from 1. to 2) across a blank line produces two separate <ol> elements with the second preserving start="2". Test case 10006 asserts that switching bullet markers from - to + across a blank line produces two separate <ul> elements. No modifications to existing test logic or expectations.

Possibly related PRs

• biomejs/biome#9717 — Modifies list end and blank-line lookahead logic in the parser that directly affects list-splitting and start-attribute preservation behaviour tested by these new cases.

Suggested reviewers

• dyc3

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes the main change: adding regression tests for mixed list markers across blank lines in markdown.
Description check	✅ Passed	The description is well-related to the changeset, providing context, linked issues, and test verification steps.
Linked Issues check	✅ Passed	The PR adds regression tests that directly address both issues #9729 and #9731 by verifying separate list generation when delimiters/markers change across blank lines.
Out of Scope Changes check	✅ Passed	Changes are tightly scoped—only adding two new test cases to verify existing parser behaviour with no unrelated modifications.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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