test: migrate stats/chi2gof to ULP-based assertions

[kgryte]

Resolves a part of #11352.

Description

What is the purpose of this pull request?

This pull request:

• migrates the tests for stats/chi2gof from relative tolerance assertions to ULP-based assertions using @stdlib/assert/is-almost-same-value, following the idiom established in the already-migrated sibling stats/chi2test.
• removes the now unused @stdlib/math/base/special/abs and @stdlib/constants/float64/eps requires, along with the associated delta/tol declarations.
• updates test/test.js only. No other test file in the package contains relative tolerance assertions, and the package has no native (*.native.js) tests.

ULP measurement

Each converted assertion was swept downward from a high bound to the minimum integer that still passes over the full fixture set:

Test	Assertion	Actual	Expected	Min. ULP
... (when y is array of probabilities)	out.pValue	0.04059404334478123	0.0405940433447812	4
... (when y is array of probabilities)	out.statistic	9.990143369175627	9.99014336917563	2
... (when y is array of expected counts)	out.pValue	0.04059404334478123	0.0405940433447812	4
... (when y is array of expected counts)	out.statistic	9.990143369175627	9.99014336917563	2

Accordingly, the final bounds are 4 ULP for pValue and 2 ULP for statistic. Lowering either bound by one (3 and 1, respectively) causes the corresponding assertions to fail, confirming these are the tightest bounds. The package test suite was run twice at the final bounds and produced identical, passing results, confirming determinism.

Test cases that already asserted exact equality via t.strictEqual were left untouched.

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.

Opened as a draft pending CI.

make eslint-tests TESTS_FILTER=".*/stats/chi2gof/.*" reports no errors (only two pre-existing FIXME warnings on untouched lines). The editorconfig-checker binary could not be downloaded in the environment used to author this change, so EditorConfig conformance (LF endings, tab indentation, no trailing whitespace, final newline) was verified manually instead.

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.

This PR was written by Claude Code running as an unattended scheduled task. The agent studied the already-migrated sibling package stats/chi2test to mirror the established idiom, applied the conversion, and determined the minimum ULP bounds empirically by sweeping bounds against the fixture values.

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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/chi2gof	$\\color{red}955/983$ $\\color{green}+97.15\\%$	$\\color{red}103/114$ $\\color{green}+90.35\\%$	$\\color{red}13/15$ $\\color{green}+86.67\\%$	$\\color{red}955/983$ $\\color{green}+97.15\\%$

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