test: rebalance default and slow test coverage

[acgetchell]

• Promote bounded 3D and 4D invariant coverage into the default suite.
• Limit debug timeout relief to two platform-sensitive periodic builder tests.
• Document catalog-based ownership for remaining slow-test cases.

Closes #500

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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Reviewing files that changed from the base of the PR and between 156147f and 2e85901.

📒 Files selected for processing (3)

• .config/nextest.toml
• docs/dev/commands.md
• docs/dev/testing.md

🚧 Files skipped from review as they are similar to previous changes (2)

• docs/dev/commands.md
• docs/dev/testing.md

---

Walkthrough

The change updates nextest timeout handling, documents the slow-tests workflow, and enables selected 3D and 4D tests in the default suite. Five-dimensional property tests remain feature-gated.

Changes

Slow-test policy

Layer / File(s)	Summary
Timeout and execution policy .config/nextest.toml, docs/dev/commands.md, docs/dev/testing.md, justfile, tests/README.md, tests/regressions.rs	Selected tests receive 60-second overrides. Documentation defines timeout budgets, slow-test execution, feature-gated doctests, and nextest discovery checks.
Default dimensional coverage tests/benchmark_flip_fixtures.rs, tests/proptest_*.rs	Selected 3D and 4D benchmark and property tests no longer require slow-tests. Five-dimensional variants remain gated.
Periodic test coverage tests/proptest_toroidal.rs, tests/triangulation_builder.rs	Periodic quotient helpers and toroidal builder validation now run without slow-tests.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 2e859

This test-coverage and documentation change is merge-ready after normal checks and review, with no actionable merge-blocking risk remaining.

Possibly related PRs

• acgetchell/delaunay#415: Related timeout, slow-test gating, and dimensional property-test changes.
• acgetchell/delaunay#417: Related toroidal test gating and timeout changes.
• acgetchell/delaunay#499: Related builder and Delaunay property-test execution changes.

Suggested labels: documentation, rust

Poem

A rabbit checks the clocks at night,
Four-dimensional tests join the light.
Five dimensions wait behind the gate,
Toroidal builders receive more time to complete.
Slow-test paths now run just right.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the primary change: rebalancing default and slow test coverage.
Description check	✅ Passed	The description accurately covers the test promotion, timeout changes, documentation updates, and linked issue.
Linked Issues check	✅ Passed	The changes address the audit, targeted timeout, deliberate slow-test execution, and documentation objectives in [#500].
Out of Scope Changes check	✅ Passed	The test, configuration, documentation, and timeout changes are directly related to the objectives in [#500].
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 100.00%.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch test/500-slow-test-audit

---

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[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

View in Codacy

🟢 Metrics 0 complexity

Metric	Results
Complexity	0

View in Codacy

🟢 Coverage ∅ diff coverage · +0.01% coverage variation

Metric	Results
Coverage variation	✅ +0.01% coverage variation (-1.00%)
Diff coverage	✅ ∅ diff coverage

View coverage diff in Codacy

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (d1d2f7f)	82353	75541	91.73%
Head commit (2e85901)	82353 (+0)	75552 (+11)	91.74% (+0.01%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#562)	0	0	∅ (not applicable)

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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Actionable comments posted: 1

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Inline comments:
In `@tests/proptest_delaunay_triangulation.rs`:
- Line 923: Update the status comment near gen_duplicate_coords_test! to state
that 4D is active in the default suite, while 5D remains gated behind
slow-tests; leave the test configuration unchanged.

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---

ℹ️ Review info

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Configuration used: Path: .coderabbit.yml

Review profile: CHILL

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📥 Commits

Reviewing files that changed from the base of the PR and between d1d2f7f and 07a0b7d.

📒 Files selected for processing (14)

• .config/nextest.toml
• docs/dev/commands.md
• docs/dev/testing.md
• tests/README.md
• tests/benchmark_flip_fixtures.rs
• tests/proptest_convex_hull.rs
• tests/proptest_delaunay_triangulation.rs
• tests/proptest_facet.rs
• tests/proptest_orientation.rs
• tests/proptest_simplex.rs
• tests/proptest_tds.rs
• tests/proptest_toroidal.rs
• tests/regressions.rs
• tests/triangulation_builder.rs

💤 Files with no reviewable changes (2)

• tests/proptest_toroidal.rs
• tests/benchmark_flip_fixtures.rs

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.72%. Comparing base (d1d2f7f) to head (2e85901).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #562      +/-   ##
==========================================
+ Coverage   91.70%   91.72%   +0.01%     
==========================================
  Files          88       88              
  Lines       82142    82142              
==========================================
+ Hits        75332    75343      +11     
+ Misses       6810     6799      -11     

Flag	Coverage Δ
unittests	91.72% <ø> (+0.01%)	⬆️

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