test(mooncake): fix -Werror violations exposed by release test builds

[nv-nmailhot]

CI now compiles tests in release (-O3 -DNDEBUG), where assert() is a no-op, exposing pre-existing -Werror issues in mooncake_backend_test.cpp:

• memType2Str / getValidationPtr fell off the end of non-void functions in the default case (assert(0) compiles out) -> add explicit returns.
• desc.len used uninitialized in allocateWrongGPUTest -> initialize it.
• ret/ret1/ret3_gen became unused (only read by compiled-out asserts) -> mark [[maybe_unused]].

Unblocks the AWS EFA validation, which builds + runs the C++ tests in release (.gitlab/build.sh + .gitlab/test_cpp.sh).

What?

Describe what this PR is doing.

Why?

Justification for the PR. If there is an existing issue/bug, please reference it. For
bug fixes, the 'Why?' and 'What?' can be merged into a single item.

How?

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architecture, approach, etc.

Summary by CodeRabbit

• Tests
  • Improved test reliability by ensuring functions return valid default values and reducing compiler warnings in test code.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Enterprise

Run ID: 98b75b3c-528f-4194-8d25-faf9636f08b8

📥 Commits

Reviewing files that changed from the base of the PR and between b775042 and b4a0c88.

📒 Files selected for processing (1)

• test/unit/plugins/mooncake/mooncake_backend_test.cpp

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📝 Walkthrough

Walkthrough

In mooncake_backend_test.cpp, the memType2Str and getValidationPtr helper functions gain sentinel return values ("UNKNOWN" and NULL) in their default branches. Six status variables across five test functions are annotated with [[maybe_unused]] to suppress compiler warnings.

Changes

Mooncake backend test warning fixes

Layer / File(s)	Summary
Sentinel return values in default branches test/unit/plugins/mooncake/mooncake_backend_test.cpp	memType2Str default branch returns "UNKNOWN" and getValidationPtr default branch returns NULL, providing valid return values when assertions are compiled out.
[[maybe_unused]] annotations on status variables test/unit/plugins/mooncake/mooncake_backend_test.cpp	ret, ret1, and ret3_gen status variables in allocateWrongGPUTest, allocateAndRegister, loadRemote, test_intra_agent_transfer, and test_inter_agent_transfer are annotated with [[maybe_unused]].

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

A bunny hopped through warnings grim,
And stamped [[maybe_unused]] on a whim.
Two branches with no path to end
Now return their values, round the bend.
"UNKNOWN" and NULL — no fright,
The compiler hops along just right! 🐇✨

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (1 warning, 1 inconclusive)

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.
Description check	❓ Inconclusive	The description provides context on why the changes were needed and details what was fixed, but does not follow the template structure with explicit What/Why/How sections.	Reorganize the description to clearly follow the template with distinct What, Why, and How sections for better clarity and consistency.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: fixing -Werror violations in mooncake tests for release builds.
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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✨ 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 nmailhot/fix-mooncake-werror

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