test(gc): de-duplicate the matrix corpus entry registered twice by #6977

[proggeramlug]

test-parity/gc_repsel_corpus.txt held 23 entries with 22 unique names — test_gap_repsel_proven_this_frozen was registered twice, both blocks added by #6977 documenting the same thing (that #6925 landed the file without registering it, tripping the UNREGISTERED gate).

Why it isn't cosmetic

The corpus drives scripts/gc_repsel_matrix.sh. A duplicated row runs that file twice per arm, which:

• inflates every reported count by 20 cells (one per arm) — the matrix run on 393a36aa4 reported 460 cells where 440 was correct;
• skews the liveness denominators the matrix prints (collected 22/23, moved-objects 22/23), which are exactly the figures used to decide whether an arm was live enough for its green cells to mean anything.

Conclusions drawn from the affected runs were unaffected — the duplicate row passes or fails identically both times — but the totals are not comparable across runs taken before and after the duplication, which matters because the campaign is tracking a delta.

Change

Dropped the second block, kept the first (its comment explains the UNREGISTERED gate). No test files added or removed; no behaviour change.

Found while re-measuring the matrix after today's GC series.

Summary by CodeRabbit

• Bug Fixes

  • Corrected a duplicated entry in the GC representation-selection test matrix.
  • Prevented duplicate test execution and inflated result totals.
  • Restored accurate liveness and moved-object denominators for comparable results.

• Tests

  • Added GC stress coverage for a representation-selection test that performs collections.
  • Updated the test corpus classification to accurately reflect its active garbage-collection behavior.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 62b768b0-1820-4a6e-b479-51128c03bb9a

📥 Commits

Reviewing files that changed from the base of the PR and between ca384ca and 423a21d.

📒 Files selected for processing (2)

• changelog.d/7010-corpus-duplicate-entry.md
• test-parity/gc_repsel_corpus.txt

💤 Files with no reviewable changes (1)

• test-parity/gc_repsel_corpus.txt

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📝 Walkthrough

Walkthrough

The GC representation-selection corpus manifest now identifies the collection-performing stress test, and a changelog entry documents how a duplicate corpus entry inflated parity matrix cells and liveness denominators.

Changes

GC representation-selection corpus corrections

Layer / File(s)	Summary
Corpus manifest and result accounting test-parity/gc_repsel_corpus.txt, changelog.d/7010-corpus-duplicate-entry.md	The manifest updates the GC-live section for test_gap_repsel_gc_stress, while the changelog documents the duplicate test_gap_repsel_proven_this_frozen entry and its effect on matrix totals.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Possibly related PRs

• PerryTS/perry#6977: Also updates the GC representation-selection corpus and related matrix behavior.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title matches the main change: de-duplicating the GC corpus entry added by #6977.
Description check	✅ Passed	The description covers the change, rationale, and impact, but it omits explicit Related issue and Test plan sections from the template.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/corpus-duplicate-entry

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