test: migrate stats/base/dists/frechet/kurtosis to ULP-based assertions

[kgryte]

Description

What is the purpose of this pull request?

This pull request:

• migrates the tests for stats/base/dists/frechet/kurtosis from computed EPS-based tolerances 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.
• replaces the delta/tol fixture comparisons in both test/test.js and test/test.native.js with t.strictEqual( isAlmostSameValue( y, expected[ i ], 1782 ), true, 'returns expected value' );.
• removes the now unused @stdlib/math/base/special/abs and @stdlib/constants/float64/eps requires.

ULP bound: 1782 in both test/test.js and test/test.native.js.

The bound was tightened agentically: starting from a high value and lowering it to the minimum integer which still passes over the full fixture set (100 cases in test/fixtures/julia/data.json). The measured maximum ULP difference across the fixtures is exactly 1782 (worst case: alpha = 8.257982161629817, s = 3.5752261675814747, actual 10.571830630166573 vs. expected 10.571830630163408); N = 1781 fails one case, so 1782 is the tightest bound which passes. The suite was run repeatedly at the final value with identical results (115/115 assertions passing each run), so the bound is not arch/FMA sensitive on this machine. The previous tolerances were 1350.0 * EPS * abs( expected ) (JS) and 1500.0 * EPS * abs( expected ) (native), which correspond to roughly the same magnitude.

Consistent with the convention in previously converted packages in this family (e.g. stats/base/dists/frechet/mode), the same ULP bound is used in test.js and test.native.js. Note that the native tests are skipped in this environment because the native add-on is not built, so the native bound is inherited from the JavaScript measurement rather than independently measured.

Only test files are changed; no implementation or fixture changes.

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.

make eslint-tests TESTS_FILTER=".*/stats/base/dists/frechet/kurtosis/.*" passes with 0 errors (the only remaining output is the pre-existing Unknown word: "échet" cspell warning, which is also present on already-migrated files in this family).

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 written primarily by Claude Code, which performed the test migration and measured the minimum passing ULP bound.

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@stdlib-js/reviewers

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Generated by Claude Code

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/base/dists/frechet/kurtosis	$\\color{red}205/208$ $\\color{green}+98.56\\%$	$\\color{red}12/13$ $\\color{green}+92.31\\%$	$\\color{green}2/2$ $\\color{green}+100.00\\%$	$\\color{red}205/208$ $\\color{green}+98.56\\%$

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