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Evidenceqs-45

Cannot parse mix of simple array and explicit array.

qs#45, at commit 5ac9df5. A closed issue from a repository Credda did not choose.

LIVE2026-09-20

RIGHT_FAILURE

executed against the upstream checkout.

Outcome
REPRODUCED_AND_DIAGNOSED
Wall time
107.7s
Checks
5 passed of 5 applicable

RECORDED

NOT_GRADED

graded from the transcript committed with this case.

Outcome
not recorded
Checks
none run
Repository
ljharb/qs
Issue
#45
Pinned commit
5ac9df501fc9c5266fc3d055a5ec5e740d182364

01The signal

The report, exactly as it was filed.

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

qs#45 · as filedcommit 5ac9df5

Cannot parse mix of simple array and explicit array.

The following testcase would fail:

``` javascript
    it('parses mix of simple and explicit array', function (done) {

        expect(Qs.parse('a=b&a[]=b')).to.deep.equal({ a: ['b', 'b'] });
        expect(Qs.parse('a[]=b&a=b')).to.deep.equal({ a: ['b', 'b'] });
        done();
    });
```

Not sure if above is valid testcase to be honest.
Repository
ljharb/qs
Issue
#45
Commit
5ac9df501fc9c5266fc3d055a5ec5e740d182364
Why this commit
The first parent of the fix commit 9c69ef4714d5a990dd16d2e5f68005e68d676556, which GitHub binds to this issue via CLOSED_EVENT_COMMIT. 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
Qs.parse('a=b&a[]=b') does not produce { a: ['b', 'b'] }; the fix makes it do so.
Expression
Qs.parse('a=b&a[]=b')
Where that came from
Read mechanically from the report's fenced code, ASSERTION form: `expect(Qs.parse('a=b&a[]=b')).to.deep.equal({ a: ['b', 'b'] });`.

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
`Qs.parse('a=b&a[]=b')` still produces { a: ['b', 'b'] } (read { a: 'b' })
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.

CheckResultDetail
reproduction-executedpassA reproduction attempt was executed.
signature-capturedpass`Qs.parse('a=b&a[]=b')` still produces { a: ['b', 'b'] } (read { a: 'b' })
right-failurepassReproduced the reported failure: Qs.parse('a=b&a[]=b') does not produce { a: ['b', 'b'] }; the fix makes it do so.
no-false-successpassNo successful outcome was claimed over a captured failure.
no-unproven-successpassNo 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 5ac9df5, 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/ljharb/qs
git checkout 5ac9df501fc9c5266fc3d055a5ec5e740d182364
npm install

CREDDA_PROVIDER=heuristic \
  npx tsx apps/cli/src/main.ts fix <repo-path> @<issue-file> --no-color
Read the full studyAll 158 cases