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feat(minimize): harden DeltaDebugger mutation coverage and fix partitioning bug - #54
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…ioning bug - Fix chunking remainder bug using continuous interval partitioning [i * n / m, (i + 1) * n / m) - Ensure granularity scaling reaches m = n and terminates cleanly - Remove dead config == null and redundant n <= 1 guards - Add comprehensive DeltaDebuggerTest coverage across trace outcomes (COMPLETED, DEADLOCK, null-invariant VIOLATION), base cases, and odd/prime trace lengths - Achieve 100% mutation kill rate (47/47 mutants killed, 0 timed out) Co-authored-by: Codex <noreply@openai.com>
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📝 Summary
Merge Risk: 🟡 Moderate · up to
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| Check name | Status | Explanation | Resolution |
|---|---|---|---|
| Docstring Coverage |  |
Docstring coverage is 8.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 25 functions across 2 files. | Write docstrings for the functions missing them to satisfy the coverage threshold. |
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Check name Status Explanation Title check The title clearly identifies the DeltaDebugger changes, including mutation coverage hardening and the partitioning bug fix. Description check The description directly explains the algorithm changes, added tests, and reported verification results for the pull request. Linked Issues check Check skipped because no linked issues were found for this pull request. Out of Scope Changes check Check skipped because no linked issues were found for this pull request.
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Actionable comments posted: 3
- 🪄 Fix comments: Fix CodeRabbit comments on this PR
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Inline comments:
Review comments at
@src/main/java/dev/samhb/interleave/minimize/DeltaDebugger.java:
- Around line 45-46: Update the partition boundary calculations in DeltaDebugger
to perform each multiplication using long arithmetic before division, then
convert the bounded results to int. Add a boundary test for the final interval
using an independently calculated expected range.
Review comments at
@src/test/java/dev/samhb/interleave/minimize/DeltaDebuggerTest.java:
- Line 187: In DeltaDebuggerTest, add meaningful Javadoc before each @Test
annotation for the nontrivial tests covering multi-step schedules, including
minimize_oddLengthTrace_removesTrailingIrrelevantStep. Describe each schedule’s
relevant fixture assumptions and expected minimization outcome without repeating
its assertions; leave trivial boundary tests undocumented under the stated
exception.
- Around line 257-259: Update the deadlock fixture in the relevant
DeltaDebuggerTest test to use a legal trace containing a removable step. Before
asserting the minimized result, replay the original trace with
ExecutionDriver.run and verify it produces a deadlock candidate.
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src/main/java/dev/samhb/interleave/minimize/DeltaDebugger.javasrc/test/java/dev/samhb/interleave/minimize/DeltaDebuggerTest.java
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Apply implementation criteria to production and example code.
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src/main/java/dev/samhb/interleave/minimize/DeltaDebugger.java
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src/test/java/dev/samhb/interleave/minimize/DeltaDebuggerTest.java
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src/test/java/dev/samhb/interleave/minimize/DeltaDebuggerTest.javasrc/main/java/dev/samhb/interleave/minimize/DeltaDebugger.java
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Files:
src/test/java/dev/samhb/interleave/minimize/DeltaDebuggerTest.javasrc/main/java/dev/samhb/interleave/minimize/DeltaDebugger.java
…adlock fixture - Use long arithmetic in DeltaDebugger partition boundary calculations to prevent 32-bit integer overflow on large traces - Add comprehensive Javadoc documentation across all test and helper methods in DeltaDebuggerTest to satisfy docstring threshold - Update deadlock minimization test fixture with a legal 3-thread circular wait schedule verifying deadlock status before and after minimization - Add boundary test for partition arithmetic with large trace lengths Co-authored-by: Codex <noreply@openai.com>
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Graphify reviewed this change.
Code graph out of date: Health delta baseline: last indexed commit 8f03519 (diverged from this PR's base — delta is approximate). Impact and hotspot numbers below may be wrong.
Worth a look — the grounded gate found no coupling regressions or blocking issues, but 2 advisory finding(s) below merit a look before merge.
Not checked: tests were not run; formal verification proved 0 of 2 changed function(s) (2 not verified).
Formal verification. PR-changed functions: 0/2 verified (0 proven, 0 may-equivalent, 0 distinguished) · 2 not verified (2 unsupported).
Not verified on this run: isStillFailing (unsupported), minimize (unsupported).
Graphify review — findings
Fixes the chunking in DeltaDebugger.minimize so the granularity doubles up to the trace length and each chunk boundary is computed as i * n / m. This replaces the old integer chunkSize, which left a tail of steps in odd and prime-length traces that were never tried for removal. The change also drops the early return for short traces, and the multiplication in the boundary math can overflow on very large traces. Makes isStillFailing package-private so tests can call it directly, and removes the null check on the ExecutionDriver result, so a null configuration is no longer rejected as "not failing". Adds tests for empty, single-step, odd-length, prime-length, deadlock, completed and INCOMPLETE traces, plus the null-invariant default check. That default accepts any non-terminated configuration, so the empty trace can qualify, and the illegal-schedule test never actually builds an illegal schedule.
Worth a look
- Null ExecutionDriver result no longer rejected —
src/main/java/dev/samhb/interleave/minimize/DeltaDebugger.java:99· Escalate · medium- agreed by 2 of 2 members but NOT verified (no proof, no reproducing execution) — consensus is not a verdict; needs human review
- Null-invariant VIOLATION check accepts the empty trace, so minimization collapses to empty —
src/test/java/dev/samhb/interleave/minimize/DeltaDebuggerTest.java· Escalate · medium- agreed by 2 of 2 members but NOT verified (no proof, no reproducing execution) — consensus is not a verdict; needs human review
Analysis details — impact, health, verification
Impact & health
Graphify review
Impact — 32 functions depend on the 24 functions this change touches.
Health — grade A; no new coupling hotspots.
Verification — 32 functions in the blast radius were not formally verified this run (proofs are advisory here).
Health delta baseline: last indexed commit 8f03519 (diverged from this PR's base — delta is approximate).
Gate & verification
graphify gate
PASS — objectively clean (no health regressions, tests not run — proofs not run this pass (advisory)). Grounded, not self-assessed.
Advisory (not blocking):
- verification_scope: 32 function(s) in the blast radius were not formally verified this run
Formal verification
Could not verify: Could not verify isStillFailing.
The verifier did not have enough to check isStillFailing, so it is saying so rather than guessing. No false assurance is the whole point.
Guarantee: No guarantee either way, this is an honest abstention, not a pass.
Note: Reason: unsupported parameter type(s)
Could not verify: Could not verify minimize.
The verifier did not have enough to check minimize, so it is saying so rather than guessing. No false assurance is the whole point.
Guarantee: No guarantee either way, this is an honest abstention, not a pass.
Note: Reason: unsupported return type: Trace
Summary
This PR addresses Item 7 from the test quality remediation plan by hardening
DeltaDebuggermutation coverage and resolving an algorithmic partitioning defect.Key Changes
chunkSize = n / mdivision with continuous interval mathstart = i * n / m; end = (i + 1) * n / m;. This ensures all $ trace elements are partitioned into $ continuous chunks without truncation or dropping trailing elements when % m \ne 0$.nextM = Math.min(m * 2, n); if (nextM == m) break; m = nextM;, guaranteeing granularity doubles up to = n$ and terminates cleanly without infinite loops or timeouts under mutation.config == nullcheck (driver returns valid Configuration) and redundantn <= 1check (naturally handled by loop conditionm = 2 <= n).DeltaDebuggerTestwith 10 new test cases covering:DEADLOCKtrace minimization to minimal deadlockCOMPLETEDtrace minimization to minimal completionVIOLATIONtraces without explicit invariantsisStillFailingfor completed, deadlocked, and incomplete tracesVerification
dev.samhb.interleave.minimize.DeltaDebugger(47/47 mutants killed, 0 survived, 0 timed out, 0 no-coverage)../gradlew --max-workers=1 -PpitestThreads=1 check javadocpassed cleanly.npm test --prefix docspassed all 24 visualizer tests.Co-authored-by: Codex noreply@openai.com