test: migrate stats/incr/mmeanvar to ULP-based assertions

[kgryte]

Resolves a part of #11352.

Description

What is the purpose of this pull request?

This pull request:

• migrates stats/incr/mmeanvar tests from relative tolerance (EPS) comparisons to ULP-based assertions using @stdlib/assert/is-almost-same-value.
• replaces the single computed-tolerance assertion in test/test.js with t.strictEqual( isAlmostSameValue( actual[ 1 ], expected[ 1 ], 0 ), true, 'returns expected value' ); and removes the now-unused abs and EPS requires, along with the delta and tol locals.

ULP bound

The package has a single relative-tolerance assertion (the unbiased sample variance returned by the accumulator for the fixed input [ 2.0, 3.0, 10.0 ]). The measured ULP difference between the computed and expected values is 0, so the final ULP constant is 0 (i.e., the computed value is exactly representable and bit-for-bit equal to the expected value). The previous tolerance (EPS * 19.0, roughly 1 ULP at that magnitude) was looser than required.

The package test suite was run three times at the final ULP value to confirm determinism; all 424 assertions pass on each run. Only test/test.js is changed; the package has no test/test.native.js.

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.

The repository's make lint-editorconfig-files target could not be run in this environment, because the editorconfig-checker binary is downloaded from a GitHub release that is unreachable from the sandbox. The changed file was checked manually for the relevant EditorConfig properties (LF line endings, tab indentation, no trailing whitespace, single trailing newline). make eslint-tests TESTS_FILTER=".*/stats/incr/mmeanvar/.*" passes.

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, running as an unattended task. The agent studied prior ULP migration commits in this repository, applied the migration to a single package, measured the minimum passing ULP value, and verified the package tests and test linting locally.

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🤖 Generated with Claude Code

https://claude.ai/code/session_01JiDQWpZ5HtMarEZL1zWjrU

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Coverage Report

Package	Statements	Branches	Functions	Lines
stats/incr/mmeanvar	$\\color{green}324/324$ $\\color{green}+100.00\\%$	$\\color{green}38/38$ $\\color{green}+100.00\\%$	$\\color{green}2/2$ $\\color{green}+100.00\\%$	$\\color{green}324/324$ $\\color{green}+100.00\\%$

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