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

[Planeshifter]

Resolves a part of #11352.

Description

What is the purpose of this pull request?

This pull request:

• Migrates stats/incr/nanmcv's test/test.js from relative-tolerance (EPS-based) floating-point assertions to ULP-based assertions using @stdlib/assert/is-almost-same-value.
• Removes the manual delta/tol computations (and the now-unneeded abs and EPS requires) in favor of t.strictEqual( isAlmostSameValue( actual, expected, N ), true, 'returns expected value' ), mirroring the idiom used in previously merged conversions for other stats/incr/* packages (e.g., stats/incr/mgmean, stats/incr/mse).
• Uses the minimum required ULP value for each of the 5 converted assertions, determined empirically: all 5 sites pass at 0 ULPs (exact match) over the full fixture set (396 total tape assertions in the file).
• Verified minimality: 0 is the smallest possible non-negative integer, so this is by construction the tightest bound. The full suite was run three times at this value with identical (fully passing) results, confirming determinism (no FMA/arch 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.

Verified via:

NODE_PATH=$(pwd)/lib/node_modules npx tape lib/node_modules/@stdlib/stats/incr/nanmcv/test/test.js

396/396 assertions pass, run three times to confirm determinism. eslint run against the changed file reports no issues. Only test/test.js was changed; there is no test.native.js for this package, and no package.json dependency changes were needed since @stdlib/assert is resolved via the monorepo's NODE_PATH.

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 by Claude Code (an autonomous coding agent), which searched for a qualifying candidate package (checking for collisions against existing open/merged ULP-migration PRs), studied prior merged conversions for the same idiom, performed the migration, and empirically determined the minimum ULP bounds described above by running the full test suite and confirming tightness/determinism through repeated runs.

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@stdlib-js/reviewers

🤖 Generated with Claude Code

https://claude.ai/code/session_01D2sx1F2BHVSaL578CQbn3f

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Generated by Claude Code

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/incr/nanmcv	$\\color{green}152/152$ $\\color{green}+100.00\\%$	$\\color{green}10/10$ $\\color{green}+100.00\\%$	$\\color{green}2/2$ $\\color{green}+100.00\\%$	$\\color{green}152/152$ $\\color{green}+100.00\\%$

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