test: make omitted cluster comments optional

[renecannao]

Summary

• treat an omitted comment in expected cluster-simulator states as a wildcard
• preserve exact comparison when comment is explicitly present, including an empty string
• include specified comments in projected diagnostic JSON
• add a focused TAP regression and run it in the cluster-simulator CI build

Root cause

The Galera simulator payloads intentionally omit optional server comments. Runtime rows can retain generated comments such as node_127.1.1.x, but the parser previously converted an omitted expected comment to an empty string and the matcher compared it unconditionally. This made the first Galera payload depend on startup state and produced a checksum mismatch even though every asserted field matched.

This failure was observed while investigating PR #6017, but that PR does not modify the simulator. This fix is intentionally isolated.

Semantics

• omitted optional fields remain unconstrained
• explicit comments are compared exactly
• explicit empty comments remain distinct from omission
• checksum behavior is unchanged

Validation

• clean containerized cluster-simulator build with -j32
• focused common_utils_unit-t: 9/9
• cluster_sim_galera-g1: 5/5, repeated in two fresh isolated environments
• cluster_sim_read_only-g1: 9/9
• simulation runtime verification for both groups
• shellcheck test/infra/control/cluster-simulator-ci.bash
• git diff --check

Summary by CodeRabbit

• New Features

  • Cluster simulator status checks now support optional comments: omitted comments act as wildcards, while supplied comments—including empty values—must match exactly.
  • Status diagnostics include the comment field only when it was explicitly provided.

• Documentation

  • Documented optional status fields and their matching behavior.

• Tests

  • Added regression coverage for omitted, matching, differing, and empty comments.
  • Integrated simulator checks into the build and validation workflow.

[coderabbitai]

📝 Walkthrough

Walkthrough

The cluster simulator now tracks whether comment was supplied, treats omitted comments as wildcards, preserves exact matching for supplied comments including empty strings, and conditionally serializes comments. Focused TAP tests and CI wiring validate the behavior.

Changes

Optional cluster-simulator comments

Layer / File(s)	Summary
Comment contract and status shape docs/superpowers/..., test/deps/cluster_simulator/lib/common_utils.h, test/deps/cluster_simulator/README.md	The design, plan, API documentation, and server_status representation define presence-aware comment matching.
Presence-aware parsing and projection test/deps/cluster_simulator/lib/common_utils.cpp	Parsing records comment presence. Matching skips omitted expected comments. JSON includes comment only when supplied.
Focused regression validation and CI wiring test/deps/cluster_simulator/tests/common_utils_unit-t.cpp, test/deps/cluster_simulator/Makefile, test/infra/control/cluster-simulator-ci.bash	TAP assertions cover comment extraction, matching, and serialization. The Makefile and CI run the test binary.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related PRs

• sysown/proxysql#5760: Introduced the cluster simulator status extraction, matching, and JSON serialization extended here.

Suggested reviewers: wazir-ahmed

Poem

A rabbit checks each comment bright,
Empty or filled, it matches right.
Omitted fields can softly roam,
JSON leaves them safely home.
TAP hops green through CI’s run.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% 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
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.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: omitted cluster comments now act as optional constraints.

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/cluster-simulator-optional-comment

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[gitar-bot]

Code Review ✅ Approved

Makes omitted cluster-simulator comments optional by treating them as wildcards while preserving exact comparison for explicitly provided comments. No issues found.

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 53.04%. Comparing base (b4c7514) to head (778db5f).
⚠️ Report is 76 commits behind head on v3.0.

Additional details and impacted files

@@            Coverage Diff             @@
##             v3.0    #6022      +/-   ##
==========================================
- Coverage   53.06%   53.04%   -0.02%     
==========================================
  Files         478      478              
  Lines      143736   143736              
  Branches    36348    36348              
==========================================
- Hits        76267    76244      -23     
- Misses      50559    50584      +25     
+ Partials    16910    16908       -2     

Flag	Coverage Δ
integration-tests	49.25% <ø> (-0.02%)	⬇️
unit-tests	14.36% <ø> (ø)

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