ROX-35909: Test_OutputQueue_ExpiringMessage fails in PubSub

[jschnath]

Description

Fixes test flakes in Test_OutputQueue_ExpiringMessages and Test_OutputQueue_ForwardMessages that caused intermittent CI failures.

Root Cause:
In pubsub mode, event processing is asynchronous (occurs in a separate goroutine via the lane's run() method). The tests set a mock expectation, send
an event, validate the assertion, then immediately finish without waiting for async processing to complete. This creates a race: if the test completes
before the lane's goroutine processes the event, gomock cleanup detects the missing call and fails the test.

Fix:
Rewrite all output queue tests to use testing/synctest, matching the pattern already established in other pubsub async tests (e.g. detector_serializer_test.go). synctest.Test provides deterministic goroutine scheduling, and synctest.Wait() ensures all spawned goroutines have settled before assertions run — eliminating both the race condition and wall-clock timeouts.

Validation:

• Reproduced the flake on master with go test -count=200 -parallel=8 (failed immediately)
• Fixed version passes 200 iterations with high parallelism (600 pubsub=true executions)
• All package tests pass (go test -count=20 with zero flakes)

Introduced in PR #20898 (ROX-34880: Refactor resolver to use PubSub)

🤖 This PR was created with AI assistance.

User-facing documentation

• CHANGELOG.md is updated OR update is not needed ← not needed (test-only fix)
• documentation PR is created and is linked above OR is not needed ← not needed (test-only fix)

Testing and quality

• the change is production ready: the change is GA, or otherwise the functionality is gated by a feature flag ← test-only change
• CI results are inspected

Automated testing

• modified existing tests ← replaced channel+timeout synchronization with synctest

How I validated my change

1. Reproduced the flake on master: go test -count=200 -parallel=8 failed with missing call(s) to *mocks.MockDetector.ReprocessDeployments
2. Verified fix: Same command on fixed version passes all 200 iterations (600 pubsub=true test executions)
3. Full package tests: go test -count=20 passes with zero flakes

[coderabbitai]

📝 Walkthrough

Walkthrough

Output queue tests replace timeout-based asynchronous waits with testing/synctest, immediate forwarding assertions, and simplified mock expectations across expiration, forwarding, detector, and stop-request scenarios.

Changes

Output queue test synchronization

Layer / File(s)	Summary
Synchronization assertion foundation sensor/kubernetes/eventpipeline/output/output_test.go	Adds testing/synctest, removes the timeout constant, and replaces time-based forwarding helpers with immediate channel assertions.
Deterministic output queue scenarios sensor/kubernetes/eventpipeline/output/output_test.go	Expiration, forwarding, detector, and stop-request tests use synctest.Wait() instead of completion channels and timeout-based waits, with non-argument-specific reprocessing expectations.

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

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
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.
Title check	✅ Passed	The title is concise and matches the main test-flake fix, though it only names one affected test.
Description check	✅ Passed	The description covers the required sections, explains the fix, and includes validation and testing details.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch jschnath/bugfix/ROX-35909_Test_OutputQueue_ExpiringMessage_fails_in_pubsub

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[jschnath]

@coderabbitai full review

[coderabbitai]

✅ Action performed

Full review finished.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 51.36%. Comparing base (b3a080f) to head (978f957).
⚠️ Report is 6 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #21903      +/-   ##
==========================================
- Coverage   51.40%   51.36%   -0.04%     
==========================================
  Files        2857     2857              
  Lines      178776   178776              
==========================================
- Hits        91891    91837      -54     
- Misses      78865    78898      +33     
- Partials     8020     8041      +21     

Flag	Coverage Δ
go-unit-tests	51.36% <ø> (-0.04%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[github-actions]

🚀 Build Images Ready

Images are ready for commit 4d2381e. To use with deploy scripts:

export MAIN_IMAGE_TAG=4.12.x-583-g4d2381ef8f

[jschnath]

/retest

[vikin91]

Good idea for the fix! I am proposing to go one step further (sorry, I am a big synctest fan 😉 ).

[jschnath]

Okay, I've switched them to use synctest 👍

[vikin91]

Looks good! Thanks for improving!
You may want to update the PR description before merging as it still suggests that a solution with a channel is used.