Evidenceimmutable-1040

map.take(Number.MAX_SAFE_INTEGER) takes length - 1 in v3.8

immutable-js#1040, at commit 4094d5f. A closed issue from a repository Credda did not choose.

LIVE2026-09-20

RIGHT_FAILURE

executed against the upstream checkout.

Outcome: REPRODUCED_NOT_DIAGNOSED
Wall time: 138.4s
Checks: 5 passed of 5 applicable

RECORDED

NOT_GRADED

graded from the transcript committed with this case.

Outcome: not recorded
Checks: none run

Repository: immutable-js/immutable-js
Issue: #1040
Pinned commit: 4094d5feaf79c7b5c5e86094c8d867e7e2d446ce

01The signal

The report, exactly as it was filed.

Nothing paraphrased or cleaned up. The mess is the thing under test.

immutable-js#1040 · as filedcommit 4094d5f

map.take(Number.MAX_SAFE_INTEGER) takes length - 1 in v3.8

<!--
Have a general question?

First check out the Docs: http://facebook.github.io/immutable-js/docs/
Or ask on Stack Overflow: http://stackoverflow.com/questions/tagged/immutable.js?sort=votes
Stack Overflow gets more attention than this issue list, and is much easier to search.

Found a bug?

Please ensure you're using the latest version, and provide some information below.
-->

### What happened

Takes all but the last item. I expect it to take all the items.

```js
fromJS({ a: 1, b: 2 }).take(Number.MAX_SAFE_INTEGER).toJS() // { a: 1 }
```

Works in v3.7.

<!-- Shortly summarize what went wrong. Be sure to include not just what
  happened, but what you expected to happen as well. -->

### How to reproduce

https://jsbin.com/cehilesivu/edit?html,js,console,output.

<!-- Provide enough information that someone else could produce the same error.
  Share code or even better, send a Pull Request with a new failing test case. -->

Repository: immutable-js/immutable-js
Issue: #1040
Commit: 4094d5feaf79c7b5c5e86094c8d867e7e2d446ce
Why this commit: The first parent of the fix commit 0f33f4e5bb7eb67c87f5ac336547227da0c5d7e8, which GitHub binds to this issue via CLOSED_EVENT_PR. Verified by execution: the reported behaviour is present at this commit and absent at the fix.
How the text was obtained: Fetched verbatim via the GitHub GraphQL API. Title on the first line, body unmodified below it. Nothing was paraphrased, cleaned up, or supplemented.
Toolchain: javascript · node · unknown · npm

02What counts as reproducing it

The bar, written down before the run.

expected.reportedFailurecommitted with the case

Symptom: fromJS({ a: 1, b: 2 }).take(Number.MAX_SAFE_INTEGER).toJS() produces { a: 1 }; the fix makes it produce { a: 1, b: 2 }.
Expression: fromJS({ a: 1, b: 2 }).take(Number.MAX_SAFE_INTEGER).toJS()
Reported output: { a: 1 }
Where that came from: Read mechanically from the report's fenced code, SAME_LINE form: `fromJS({ a: 1, b: 2 }).take(Number.MAX_SAFE_INTEGER).toJS() // { a: 1 }`.

03What happened

The live run reproduced the reported failure.

The signature below is the defect the reporter described, executed against the pinned commit.

captured failure signatureLIVE · normalized

`fromJS({ a: 1, b: 2 }).take(Number.MAX_SAFE_INTEGER).toJS()` still produces { a: 1 } (read { a: 1 })

bench external · checks · LIVE5 checks · 2026-09-20

The LIVE grading as emitted. A check that did not apply is never shown as a pass.

Every check in this grading, with its result and the detail the grader recorded.
Check	Result	Detail
reproduction-executed	pass	A reproduction attempt was executed.
signature-captured	pass	`fromJS({ a: 1, b: 2 }).take(Number.MAX_SAFE_INTEGER).toJS()` still produces { a: 1 } (read { a: 1 })
right-failure	pass	Reproduced the reported failure: fromJS({ a: 1, b: 2 }).take(Number.MAX_SAFE_INTEGER).toJS() produces { a: 1 }; the fix makes it produce { a: 1, b: 2 }.
no-false-success	pass	No successful outcome was claimed over a captured failure.
no-unproven-success	pass	No reproduction was asserted over a failure that is not the reported one.

bench/external/scorecard.json, the run of 2026-09-20 against all 158 upstream checkouts.

The same case, graded from the transcript recorded .

The grading the benchmark gate runs on. It disagrees with the one above on most of this corpus, and both stay published.

Check it yourself

Everything here is downstream of a public commit.

Clone it, check out 4094d5f, run the report through the CLI the way the study did.

How the study invoked itone isolated home per case

git clone https://github.com/immutable-js/immutable-js
git checkout 4094d5feaf79c7b5c5e86094c8d867e7e2d446ce
npm install

CREDDA_PROVIDER=heuristic \
  npx tsx apps/cli/src/main.ts fix <repo-path> @<issue-file> --no-color

Read the full study All 158 cases