[dinwwwh]

Requested by dinwwwh · project thread

Test-only. admitsNull lets a nullable $ref pair collapse to the bare $ref only when the target holds annotations and an anyOf with a null branch. No test gave the target another keyword, so two Stryker mutants survived:

• name === 'anyOf' -> true
• (name === 'anyOf' && Array.isArray(schema.anyOf)) -> ||

The new expectation, anyOf [$ref Pet, null] where Pet is { anyOf: [pet, null], not: { type: 'null' } }, stays { anyOf: [ref, onlyNull] }, since the not can reject null. Applying each mutant by hand fails this test, and both pass without it. Stryker survivors go from 71 to 69, all equivalent (mergeNullable's ref !== undefined -> true, tagsOf's getRef(value) !== undefined -> true).

pnpm run check and pnpm test (367 tests) pass.

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Generated by Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[codspeed]

Merging this PR will not alter performance

1 warning

⚠️ 1 benchmark is dominated by system calls

System calls cannot be simulated consistently and are left out of the measure. The reported value understates the real cost. Switch to the Walltime instrument to measure them.

Learn more about system calls

See affected benchmarks

✅ 29 untouched benchmarks
⏩ 2 skipped benchmarks¹

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_{Comparing claude/project-thread-8grn3t (7c407a9) with main (22ade18)}

Footnotes

1. 2 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. ↩

[pullfrog]

✅ No new issues found.

Reviewed changes

• New regression expectation in the nullable-$ref pair suite — owner({ anyOf: [pet, { type: 'null' }], not: { type: 'null' } }) now asserts the pair stays { anyOf: [ref, onlyNull] }. The not makes the $ref target reject null, so admitsNull is false and mergeNullable must keep the explicit null branch rather than collapse to the bare $ref. The expectation is semantically correct.

I verified the mutation coverage claim empirically: both admitsNull mutants (name === 'anyOf' → true, and the && → || guard at packages/downgrader/src/v3.1-to-v3.0.ts:818) make this new assertion fail, and the file passes 122/122 unmutated.

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