br/pkg/streamhelper: stabilize flaky TestStoreRemoved

[flaky-claw]

What problem does this PR solve?

Issue Number: close #52791

Problem Summary:
Flaky test TestStoreRemoved in br/pkg/streamhelper intermittently fails, so this PR stabilizes that path.

What changed and how does it work?

Root Cause

TestStoreRemoved was flaky because it used channel-idle timing (waitPendingEvents) as a proxy for delivery completion, so post-removal events could still be in flight when Drop() canceled them.

Fix

The test needed to wait for the semantic condition it actually cares about, namely that the subscriber has observed full-span coverage at the final post-removal checkpoint.

Verification

Spec:

• target: br/pkg/streamhelper :: TestStoreRemoved
• strategy: tidb.go_flaky.default
• plan mode: BASELINE_ONLY
• requirements: required case must execute; no skip; repeat count = 1
• baseline gates: required_flaky_gate, build_safety_gate, intent_guard_gate

Observed result:

• status: passed
• required case executed: yes
• submission decision: ALLOWED
• scope debt present: yes

Gate checklist:

• Required flaky gate: PASS
• Build safety gate: PASS
• Intent guard gate: PASS
• Repo-wide advisory gate: SKIPPED
• Feedback specific gate: SKIPPED

Commands:

• go test -json ./br/pkg/streamhelper -run '^TestStoreRemoved$' -count=1
• go test -json ./br/pkg/streamhelper -count=1
• make build

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No need to test

  • I checked and no code files have been changed.

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

Fixes #52791

Summary by CodeRabbit

• Tests
  • Improved test utility by consolidating span collection and synchronization logic into a reusable helper function, reducing code duplication and enhancing test maintainability.

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No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 7777c681-f26e-4b71-8065-e99f75a1c3bb

📥 Commits

Reviewing files that changed from the base of the PR and between 874ff37 and 7243d5e.

📒 Files selected for processing (1)

• br/pkg/streamhelper/subscription_test.go

---

📝 Walkthrough

Walkthrough

Added a helper function collectCheckpointSpans to consolidate event synchronization and span collection logic in a test. Updated TestStoreRemoved to use this helper instead of manually waiting and draining events, reducing code duplication and improving reliability of the flaky test.

Changes

Cohort / File(s)	Summary
Test Synchronization Helper br/pkg/streamhelper/subscription_test.go	Introduced collectCheckpointSpans helper to wait for events until a checkpoint is reached, then merged into span collection. Refactored TestStoreRemoved to use the new helper, eliminating separate waitPendingEvents and manual event drain loop.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Suggested labels

contribution, size/XS, ok-to-test, approved, lgtm

Suggested reviewers

• YuJuncen
• Leavrth

Poem

🐰 A flaky test once made us frown,
But now a helper saves the crown!
Events synchronized with grace,
No more race conditions in this place. ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes the main change: stabilizing a flaky test in the br/pkg/streamhelper package.
Description check	✅ Passed	The PR description follows the template structure with required sections: issue number, problem summary, what changed and how, verification details, and test checklist completed.
Linked Issues check	✅ Passed	The PR addresses issue #52791 by replacing timing-based synchronization with semantic condition checking to eliminate test flakiness, directly meeting the objective.
Out of Scope Changes check	✅ Passed	All changes are within scope: a new test helper and modifications to TestStoreRemoved to stabilize the flaky test in br/pkg/streamhelper.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 golangci-lint (2.11.4)

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Leavrth, YuJuncen

The full list of commands accepted by this bot can be found here.

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Details

Needs approval from an approver in each of these files:

• br/OWNERS [Leavrth,YuJuncen]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-04-23 04:18:59.90721965 +0000 UTC m=+2225945.112579707: ☑️ agreed by YuJuncen.
• 2026-04-24 02:00:32.625691802 +0000 UTC m=+2304037.831051859: ☑️ agreed by Leavrth.

[yinsustart]

/retest

[tiprow]

@yinsustart: PRs from untrusted users cannot be marked as trusted with /ok-to-test in this repo meaning untrusted PR authors can never trigger tests themselves. Collaborators can still trigger tests on the PR using /test.

Details

In response to this:

/retest

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[yinsustart]

/check-issue-triage-complete

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.1620%. Comparing base (874ff37) to head (7243d5e).
⚠️ Report is 24 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #67954        +/-   ##
================================================
+ Coverage   77.7953%   78.1620%   +0.3666%     
================================================
  Files          1984       1992         +8     
  Lines        549728     556091      +6363     
================================================
+ Hits         427663     434652      +6989     
+ Misses       121145     120027      -1118     
- Partials        920       1412       +492     

Flag	Coverage Δ
integration	44.8377% <ø> (+5.0404%)	⬆️

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

Components	Coverage Δ
dumpling	60.4888% <ø> (ø)
parser	∅ <ø> (∅)
br	65.9359% <ø> (+2.9054%)	⬆️

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