[fix] Fix TestCaseStart/Stop events dropped for data-driven tests with shared TestCase.Id

[nohwnd]

Summary

🤖 This is an automated fix generated by the Issue Repro Triage & Auto-Fix workflow.

Fixes #4997

Root Cause

In TestExecutionRecorder.RecordStart, there was a deduplication guard that prevented sending TestCaseStart events when a test with the same TestCase.Id was already "in progress":

// Do not send TestCaseStart for a test in progress
if (!_testCaseInProgressMap.Contains(testCase.Id))
{
    _testCaseInProgressMap.Add(testCase.Id);
    _testCaseEventsHandler.SendTestCaseStart(testCase);
}

For data-driven tests where all rows share the same TestCase.Id (because their fully-qualified names are identical), this guard silently drops TestCaseStart events for row executions that overlap with the parent test's in-progress window. This causes data collectors to receive unmatched TestCaseEnd events and miss test execution data.

Fix

• Changed _testCaseInProgressMap from HashSet<Guid> to Dictionary<Guid, int> (reference counting)
• Removed the deduplication guard in RecordStart — every call now forwards a TestCaseStart event
• SendTestCaseEnd uses the reference count to ensure each TestCaseStart has exactly one matching TestCaseEnd (i.e., TestCaseEnd is still not sent if there was no preceding TestCaseStart)

Tests

• Updated RecordStartAndRecordEndShouldForwardAllTestCaseStartAndEndEvents to reflect new behavior (2 Starts and 2 Ends for 2 Start + 2 End calls)
• Added RecordStartAndRecordEndShouldSendEventsForNestedDataDrivenTestsWithSameId which directly tests the nested data-driven scenario: Start(parent) → Start(row1) → End(row1) → Start(row2) → End(row2) → End(parent) — all 3 Start/End pairs are now forwarded

All 648 CrossPlatEngine unit tests pass.

🔍 Triaged by Issue Repro Triage & Auto-Fix 🔍

[Copilot]

Pull request overview

Fixes dropped TestCaseStart/TestCaseEnd event pairing for data-driven tests where multiple executions share the same TestCase.Id, by replacing the in-progress de-duplication set with a reference-counting map and updating unit tests accordingly.

Changes:

• Switched _testCaseInProgressMap from HashSet<Guid> to Dictionary<Guid, int> to reference-count in-progress starts per TestCase.Id.
• Updated RecordStart to always forward SendTestCaseStart (no de-duplication by ID).
• Updated unit tests to expect multiple Start/End forwards and added a nested shared-Id scenario test.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/Microsoft.TestPlatform.CrossPlatEngine/Adapter/TestExecutionRecorder.cs	Reworks in-progress tracking to a reference count and forwards every TestCaseStart; adjusts TestCaseEnd emission based on count.
test/Microsoft.TestPlatform.CrossPlatEngine.UnitTests/Adapter/TestExecutionRecorderTests.cs	Updates expectations for duplicated starts/ends and adds a nested data-driven shared-Id test.

[nohwnd]

Expert Review — [fix] Fix TestCaseStart/Stop events dropped for data-driven tests with shared TestCase.Id

Dimensions activated: Parallel Execution & Scheduling Safety, Null Safety & Boundary Validation

Overall assessment

The core fix is correct for the intended scenario (flat data-driven tests where multiple rows with the same TestCase.Id are executed sequentially). The locking strategy is unchanged and sound. The RecordResult safety-net interaction needs attention — see inline comment.

What the fix does well

• The HashSet → Dictionary<Guid, int> reference-counting is the right data structure for the problem.
• SendTestCaseEnd correctly uses TryGetValue + count > 0 guard, preserving the invariant that every TestCaseEnd is preceded by a TestCaseStart.
• Thread safety: both RecordStart and SendTestCaseEnd are properly protected by _testCaseInProgressSyncObject.
• Existing tests updated correctly and new flat + nested scenarios covered.

Concern

RecordResult calls SendTestCaseEnd as a safety net (// Send TestCaseEnd in case RecordEnd was not called). With HashSet semantics this was idempotent. With reference counting it consumes a slot, which can drop the outer test's TestCaseEnd in a nested adapter call pattern where RecordResult is also invoked per row. See the inline comment for the exact reproduction sequence.

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🧠 Reviewed by Expert Code Reviewer 🧠

[nohwnd]

[Parallel Execution & Scheduling Safety] — Potential count under-run in nested + RecordResult scenario

SendTestCaseEnd is called from two places:

1. RecordEnd (explicit notification from the adapter)
2. RecordResult — as a safety net "in case RecordEnd was not called" (line ~99)

With the old HashSet semantics the safety net was harmless: once RecordEnd removed the ID the subsequent RecordResult → SendTestCaseEnd call was a no-op.

With the new reference-counting semantics the safety net consumes a count slot. Consider the nested pattern where the parent and a row share the same Guid and the adapter also calls RecordResult per row (which is the normal adapter contract):

RecordStart(parent)   → count = 1
RecordStart(row1)     → count = 2
RecordEnd(row1)       → sends End, count = 1
RecordResult(row1)    → SendTestCaseEnd: count = 1 > 0 → sends a SECOND End for row1, count = 0, entry removed
RecordStart(row2)     → count = 1
RecordEnd(row2)       → sends End, count = 0, entry removed
RecordResult(row2)    → no-op
RecordEnd(parent)     → TryGetValue = false → no-op  ← parent's End is silently dropped

Result: 3 Starts, 3 Ends — but the parent's TestCaseEnd is dropped and row1 receives a spurious extra TestCaseEnd.

The new test RecordStartAndRecordEndShouldSendEventsForNestedDataDrivenTestsWithSameId deliberately omits RecordResult calls, so this path is not exercised.

Suggested mitigation: Add a test covering Start(parent) → Start(row1) → End(row1) → Result(row1) → End(parent) to confirm the expected outcome and document whether adapters are expected to call RecordResult for individual rows in a nested scenario. If they are, the safety-net call in RecordResult may need to be guarded so it only fires when count is exactly 1 (i.e., the last in-progress context).

[nohwnd]

Good catch — the safety-net was indeed consuming a count slot that belonged to the parent.

Fix applied: added _testCaseEndCalledSet (a HashSet<Guid>) alongside the existing reference-count map.

• RecordEnd: adds the test case ID to _testCaseEndCalledSet before sending the End event. Removes it when the count reaches zero (test fully complete).
• RecordResult safety-net: now only fires if count > 0 and the ID is not in _testCaseEndCalledSet. Once any RecordEnd is called for an ID, subsequent RecordResult calls for that ID are no-ops until the ID is fully resolved.

New test added: RecordResultShouldNotSendSpuriousTestCaseEndForParentInNestedDataDrivenScenario directly tests the Start(parent) → Start(row1) → End(row1) → Result(row1) → End(parent) pattern and asserts exactly 2 SendTestCaseEnd calls (not 3). All 648 unit tests pass.

🔧 Iterated by PR Iteration Agent 🔧

[nohwnd]

Commit pushed: 9a7b32d

🔧 Iterated by PR Iteration Agent 🔧

[nohwnd]

Expert Review — [fix] Fix TestCaseStart/Stop events dropped for data-driven tests with shared TestCase.Id (iteration re-review)

Dimensions activated: Parallel Execution & Scheduling Safety

Assessment of the iteration fix

The _testCaseEndCalledSet addition correctly addresses the original finding: once any RecordEnd fires for an ID, subsequent RecordResult safety-net calls can no longer consume count slots belonging to a parent or sibling. The new test RecordResultShouldNotSendSpuriousTestCaseEndForParentInNestedDataDrivenScenario directly validates the reproduction sequence.

What the fix gets right

• _testCaseEndCalledSet is cleaned up atomically with _testCaseInProgressMap when count reaches zero — no stale state leakage.
• Lock coverage is consistent: both the count decrement and the Set operations happen under _testCaseInProgressSyncObject.
• All primary scenarios work correctly:
  • Flat data-driven rows (all call RecordEnd): ✓
  • Adapter omits RecordEnd (safety-net fires): ✓
  • Nested Start(parent) → Start(row) → End(row) → Result(row) → End(parent): ✓

Remaining concern (inline)

The _testCaseEndCalledSet guard is ID-scoped, so it broadly suppresses the safety-net for ALL rows once any row calls RecordEnd. This is harmless in practice because real adapters apply RecordEnd uniformly across rows — see inline comment for the full edge case analysis. This is best addressed with a documentation comment rather than a code change.

Description alignment

The PR description accurately reflects the root cause and the iteration agent's addendum (the _testCaseEndCalledSet addition) is documented in the thread. No misalignment.

🧠 Reviewed by Expert Code Review workflow

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🧠 Reviewed by Expert Code Reviewer 🧠

[nohwnd]

[Parallel Execution & Scheduling Safety] — Broad suppression edge case with _testCaseEndCalledSet

The _testCaseEndCalledSet guard works correctly when all rows in a nested data-driven test consistently call RecordEnd (or consistently don't). However, the suppression is ID-scoped rather than per-call, which means it can produce an incorrect outcome if an adapter's behavior is inconsistent across rows that share the same TestCase.Id:

RecordStart(parent)  → count=1
RecordStart(row1)    → count=2
RecordEnd(row1)      → adds id to _testCaseEndCalledSet, sends End, count=1
RecordResult(row1)   → id IN _testCaseEndCalledSet → no-op ✓
RecordStart(row2)    → count=2  (id still in _testCaseEndCalledSet)
RecordResult(row2)   → id IN _testCaseEndCalledSet → suppressed ← row2's End is silently dropped
RecordEnd(parent)    → sends End, count=0, removes entries

Row2 relied on the RecordResult safety-net (its RecordEnd was never called), but the safety-net was suppressed because row1 had already called RecordEnd.

Impact assessment: This is theoretical — real adapters uniformly either call RecordEnd per row or don't. A per-call counter for "ends already sent" isn't feasible without a per-invocation identifier since all rows share the same Guid. The current approach is the best achievable given the API surface.

Suggestion: Add a comment near _testCaseEndCalledSet stating this known limitation explicitly: that the guard assumes adapters apply RecordEnd uniformly across all rows sharing the same ID. This documents the design intent for future readers.

[nohwnd]

Good point. I've added a <para> block to the _testCaseEndCalledSet XML doc comment documenting this known limitation — that suppression is ID-scoped and assumes adapters apply RecordEnd uniformly across all rows sharing the same ID.

🔧 Iterated by PR Iteration Agent 🔧

[nohwnd]

Commit pushed: 83d3cc0

🔧 Iterated by PR Iteration Agent 🔧

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

[nohwnd]

All CI checks are now fully green ✅ (Windows Release, Ubuntu, macOS, Source-Build all passed — build 1424058, 2026-05-18) and all review feedback has been addressed.

This PR is ready to review but is in draft state. Please click "Ready for review" to undraft it.

🔧 Iterated by PR Iteration Agent 🔧

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