test: migrate stats/base/dists/signrank/quantile to ULP-based assertions

[kgryte]

Description

What is the purpose of this pull request?

This pull request:

• migrates the tests for stats/base/dists/signrank/quantile from relative tolerance (EPS/delta/tol) assertions to ULP-based assertions using @stdlib/assert/is-almost-same-value, per [RFC]: Migrate math/base/special packages from relative tolerance testing to ULP difference testing (tracking issue) #11352.
• updates test/test.factory.js and test/test.quantile.js (the only test files in the package which used the tolerance idiom; test/test.js contains only exact assertions and is unchanged). The package has no test.native.js.
• removes the now unused @stdlib/math/base/special/abs and @stdlib/constants/float64/eps requires and the associated delta/tol locals, while preserving the existing expected[ i ] !== null fixture guard and overall test structure.

ULP bound: 0 in both files.

The bound was tightened agentically: assertions were run against the full R fixture set (150 cases per file) and pass at 0 ULP, i.e. bit-for-bit equality, which is the tightest bound possible. This is expected here, since the signrank quantile function returns integer-valued rank statistics which are exactly representable. The full package suite (326 assertions) was run twice at the final bound with identical results, confirming no FMA/arch-dependent flakiness.

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

• [RFC]: Migrate math/base/special packages from relative tolerance testing to ULP difference testing (tracking issue) #11352

Questions

Any questions for reviewers of this pull request?

No.

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

Only test files are changed; no source, docs, or fixtures were touched.

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

AI Assistance

When authoring the changes proposed in this PR, did you use any kind of AI assistance?

• Yes
• No

If you answered "yes" above, how did you use AI assistance?

• Code generation (e.g., when writing an implementation or fixing a bug)
• Test/benchmark generation
• Documentation (including examples)
• Research and understanding

Disclosure

If you answered "yes" to using AI assistance, please provide a short disclosure indicating how you used AI assistance. This helps reviewers determine how much scrutiny to apply when reviewing your contribution. Example disclosures: "This PR was written primarily by Claude Code." or "I consulted ChatGPT to understand the codebase, but the proposed changes were fully authored manually by myself.".

This PR was authored by Claude Code. It mirrored the idiom established in previously merged conversions (e.g. #14129, #14141) and determined the minimum passing ULP bound empirically by running the package test suite.

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@stdlib-js/reviewers

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Generated by Claude Code

[stdlib-bot]

Hello! 👋

We've noticed that you've been opening a number of PRs addressing good first issues. Thank you for your interest and enthusiasm!

Now that you've made a few contributions, we suggest no longer working on good first issues. Instead, we encourage you to prioritize cleaning up any PRs which have yet to be merged and then proceed to work on more involved tasks.

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[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/base/dists/signrank/quantile	$\\color{green}305/305$ $\\color{green}+100.00\\%$	$\\color{green}45/45$ $\\color{green}+100.00\\%$	$\\color{green}4/4$ $\\color{green}+100.00\\%$	$\\color{green}305/305$ $\\color{green}+100.00\\%$

The above coverage report was generated for the changes in this PR.