test: migrate stats/incr/nanmrss 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/incr/nanmrss from a computed relative-tolerance comparison (delta = abs( expected - actual ) / tol = 1.0 * EPS * abs( expected ), asserted via t.equal( delta <= tol, ... )) to a ULP-difference assertion using @stdlib/assert/is-almost-same-value.
• applies the migration to the single tolerance-based assertion site in test/test.js. The package has no test/test.native.js. The remaining assertions in the file are exact comparisons against null, thrown TypeErrors, function types, and the exactly representable value 145.0, which are correct as-is and are left unchanged.
• removes the now-unused @stdlib/math/base/special/abs and @stdlib/constants/float64/eps requires, along with the delta and tol variable declarations.
• collapses the if ( actual === expected[i] ) { ... } else { ... } branch in the moving-residual-sum-of-squares test into a single ULP assertion, matching the migrated idiom.

Only a test file is changed; no implementation, fixture, or documentation changes are included.

ULP bounds

Assertion	Previous tolerance	ULP bound
moving residual sum of squares computed incrementally (9 values)	1.0 * EPS * abs( expected )	0

This is the minimum integer bound N such that isAlmostSameValue( actual, expected[ i ], N ) holds at the assertion site, and it is the floor of the scale — no tighter bound exists. It was measured independently of the test harness by computing ulpDifference( actual, expected[ i ] ) directly at every element, starting from a high bound (64, which passes) and tightening.

The per-element ULP differences are 0, 0, 0, 0, 0, 0, 0, 0, 0: the accumulator reproduces every expected value (1, 1, 1, 17, 26, 89, 89, 82, 154) bit-for-bit. These are small integers well within the exactly representable range, and the incremental algorithm accumulates only sums of products of small integer-valued inputs, so no rounding occurs at any step. The original test anticipated this by branching on actual === expected[i] and taking the exact-comparison path first; the pre-existing relative tolerance was never actually exercised on this platform. At N = 0, isAlmostSameValue delegates to isSameValue, so the migrated assertion preserves that exact-comparison behavior rather than loosening it.

make test TESTS_FILTER=".*/stats/incr/nanmrss/.*" was run twice at the final bound with identical results: 25/25 passing on both runs, no failures, ruling out FMA/architecture-dependent flakiness on this platform. make eslint-tests TESTS_FILTER=".*/stats/incr/nanmrss/.*" is clean.

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?

The migrated bound is 0 rather than 1. Since every value in this fixture is exact, 0 is the minimum required bound as the tracking issue asks for, and it preserves the exact comparison the original test already performed via its actual === expected[i] branch. A bound of 1 would be strictly weaker than the assertion being replaced. Flagging in case a reviewer would prefer 1 for consistency with sibling packages whose fixtures are genuinely inexact; 0 is used elsewhere in the migrated set, so this follows existing precedent.

Other

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

The resulting diff mirrors the already-merged migrations for the sibling accumulator packages stats/incr/nanmhmean (#15125), stats/incr/mmape (#15150), and stats/incr/mda (#15142), which share the same test structure.

One environment note, which did not affect verification: make install-node-modules initially failed with ETARGET for es-object-atoms@^1.1.2. As previously observed in #15116 and #15125, this is a stale local npm packument cache rather than a repository or registry problem; refetching with npm_config_prefer_online=true succeeded, after which make init and the full toolchain were available for this PR.

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

This PR was written primarily by Claude Code, running as an unattended scheduled task. It selected the package, studied previously migrated packages in the same family to match the established idiom, performed the migration, and determined the minimum passing ULP bound empirically at the assertion site.

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🤖 Generated with Claude Code

https://claude.ai/code/session_014muLqDv12CgWqs2cpTH9vW

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Coverage Report

Package	Statements	Branches	Functions	Lines
stats/incr/nanmrss	$\\color{green}155/155$ $\\color{green}+100.00\\%$	$\\color{green}8/8$ $\\color{green}+100.00\\%$	$\\color{green}2/2$ $\\color{green}+100.00\\%$	$\\color{green}155/155$ $\\color{green}+100.00\\%$

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