test: migrate stats/incr/mapcorr 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/mapcorr from relative tolerance testing to ULP difference testing, replacing the computed delta/tol comparisons with @stdlib/assert/is-almost-same-value, following the idiom established in the already migrated stats/incr/mpcorr (the signed analog of this package) and stats/incr/mpcorr2.
• switches the simulated datasets from the global PRNG seed (randu.seed) to a fixed seed (123456), which is required in order for a tightened ULP bound to be deterministic. This mirrors stats/incr/mpcorr, stats/incr/mpcorr2, and stats/incr/nanmpcorr2, which all use the same fixed seed.

Files changed (tests only):

• test/test.js

Tests which already performed exact comparisons (t.strictEqual on null, 0, exactly representable values, and NaN checks via isnan) were left untouched.

Measured ULP bounds

Each bound was tightened to the minimum integer that still passes over the full set of expected values in the corresponding test. The minima were measured programmatically (per-case minimum required ULP difference, maximized over the test's cases), and minimality was verified mechanically: decrementing any bound by one produces test failures.

Test	ULP
computes a moving sample absolute Pearson correlation coefficient incrementally	6716
computes a moving sample absolute Pearson correlation coefficient incrementally (known means)	1623
if not provided an input value, returns the current coefficient (unknown means)	1
if not provided an input value, returns the current coefficient (known means)	0
if provided NaN, the accumulated value is NaN for at least W invocations (unknown means)	1

Since mapcorr returns the absolute value of the coefficient computed by mpcorr, the measured bounds for the two fixture-driven tests (6716 and 1623) are identical to the bounds already merged for stats/incr/mpcorr, which is a useful consistency check.

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 change from randu.seed to the fixed seed 123456 is strictly speaking beyond a mechanical tolerance-to-ULP substitution, but without it the datasets differ on every run and no tight ULP bound can be stated or relied upon. The already merged stats/incr/mpcorr, stats/incr/mpcorr2, and stats/incr/nanmpcorr2 made the same change as part of their migrations, so this follows precedent; please flag if a different seed is preferred.

Other

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

• make test TESTS_FILTER=".*/stats/incr/mapcorr/.*" is green (2422 assertions passing). The suite was run twice at the final ULP values to confirm determinism.
• make lint-javascript-tests TESTS_FILTER=".*/stats/incr/mapcorr/.*" is clean.
• The package has no test/test.native.js.

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. The ULP bounds were measured programmatically rather than guessed, and each bound was verified to be minimal by confirming that one less ULP fails.

---

@stdlib-js/reviewers

🤖 Generated with Claude Code

https://claude.ai/code/session_01ECS7suxhHt53frTb9zwh3T

---

Generated by Claude Code

[stdlib-bot]

Hello! 👋

We've noticed that you've been opening a number of PRs addressing good first issues. Thank you for your interest and enthusiasm!

Now that you've made a few contributions, we suggest no longer working on good first issues. Instead, we encourage you to prioritize cleaning up any PRs which have yet to be merged and then proceed to work on more involved tasks.

Not only does this ensure that other new contributors can work on things and get ramped up on all things stdlib, it also ensures that you can spend your time on more challenging problems. 🚀

For ideas for future PRs, feel free to search the codebase for TODOs and FIXMEs and be sure to check out other open issues on the issue tracker. Cheers!

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/incr/mapcorr	$\\color{green}166/166$ $\\color{green}+100.00\\%$	$\\color{green}17/17$ $\\color{green}+100.00\\%$	$\\color{green}2/2$ $\\color{green}+100.00\\%$	$\\color{green}166/166$ $\\color{green}+100.00\\%$

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