tests: isolate pending processed regions from patrol

[rleungx]

What problem does this PR solve?

TestRaftClusterTestSuite/TestPendingProcessedRegions races with region patrol: the source region can be removed from the pending list before the exact-set assertion.

Issue Number: ref #10409

The concrete failure was observed in #11251's NextGen job. This fixes the pending-list assertion race, not the different historical failure reported in #10409.

What is changed and how does it work?

Disable region patrol before starting an isolated test environment, preventing
in-flight patrol from consuming batch-split entries before the assertion.
Preserve the exact-set assertion and clean up the environment before restoring
the failpoint. No production code changes.

Check List

Tests

• NextGen integration suite with failpoints and race detector: 5 repetitions passed (nextgen,without_dashboard).
• Classic integration suite with failpoints and race detector: 3 repetitions passed (without_dashboard).
• Configured golangci-lint: 0 issues in classic and NextGen modes (without_dashboard).
• gofmt and git diff --check: passed.
• Baseline NextGen/race run: 3 repetitions passed; the original CI failure was not reproduced in this sample.

Release note

None.

Summary by CodeRabbit

• Tests
  • Updated scheduling coverage to reliably verify that pending region-processing entries remain pending during assertions.
  • Improved test isolation by creating and cleaning up a dedicated scheduling test environment.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Advanced

Run ID: 14fbc752-e24d-43bd-81e6-d47424646af5

📥 Commits

Reviewing files that changed from the base of the PR and between ef560c8 and 4a90f13.

📒 Files selected for processing (1)

• tests/server/cluster/cluster_work_test.go

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📝 Walkthrough

Walkthrough

TestPendingProcessedRegions now controls region patrol and uses a fresh scheduling environment so pending batch-split entries remain available for the assertion.

Changes

Pending regions test

Layer / File(s)	Summary
Test setup and pending-region assertion tests/server/cluster/cluster_work_test.go	The test enables and defers disabling of skipPatrolRegions. It creates and cleans up a fresh scheduling test environment instead of reusing s.env.

Priority: ⬇️ Low

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

Change: Other

Merge Risk: ⚪ Minimal · up to 4a90f

This test-only change isolates scheduling state and restores the failpoint safely, with no established merge-blocking risk.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the test change and its purpose: isolating pending processed regions from region patrol.
Description check	✅ Passed	The description explains the race, references the issue, describes the implementation, lists validation results, and includes the required release note. The omitted optional checklist sections do not …
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 1…
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.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.75%. Comparing base (ef560c8) to head (4a90f13).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #11257      +/-   ##
==========================================
+ Coverage   79.73%   79.75%   +0.01%     
==========================================
  Files         546      546              
  Lines       79262    79262              
==========================================
+ Hits        63203    63217      +14     
+ Misses      11686    11667      -19     
- Partials     4373     4378       +5     

Flag	Coverage Δ
unittests	79.75% <ø> (+0.01%)	⬆️

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[rleungx]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: coderabbitai[bot], lhy1024

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Needs approval from an approver in each of these files:

• OWNERS [lhy1024]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-09-15 08:18:12.762698727 +0000 UTC m=+106738.700356322: ☑️ agreed by lhy1024.