fix(hack): write the coverage mode line and data to the same file

[im-Toqeer-506]

What type of PR is this?

/kind bug

What this PR does / why we need it:

Fixes the coverage output in hack/unit-test.sh.

The script was writing the coverage header and data to different files. Because of this:

• make test reported 0% coverage.
• The coverage file uploaded to Codecov was invalid because it had no mode: header.
• Running make test multiple times appended duplicate coverage data.

This PR writes the header and data to the same file and truncates the file before writing.

Which issue(s) this PR fixes:

Fixes #2933

AI assistance disclosure:
I used an AI assistant to verify the implementation and test cases. I reviewed the changes and validation results.

Hardware validation:
Not applicable. This change only affects test/coverage tooling and does not change production or device code.

Does this PR introduce a user-facing change?

NONE

AI assistance disclosure:

I used an AI assistant to verify the implementation and test cases. I reviewed the changes and validation results.

Summary by CodeRabbit

• Bug Fixes
  • Fixed coverage report generation so merged results are written to the expected output location.
  • Prevented duplicate coverage mode lines when running coverage aggregation repeatedly.

[hami-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: im-Toqeer-506
Once this PR has been reviewed and has the lgtm label, please assign dsfans2014 for approval. For more information see the Kubernetes Code Review Process.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Team

Run ID: 93f54f26-7fd4-46cb-b21b-48b131e43ab4

📥 Commits

Reviewing files that changed from the base of the PR and between e6932f5 and 207efd7.

📒 Files selected for processing (1)

• hack/unit-test.sh

Included review availability: Your plan provides up to 8 included reviews per hour; 6 remain after this review.

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📝 Walkthrough

Walkthrough

The unit test script now writes the coverage mode line and merged profile data to ./_output/coverage/coverage.out. The coverage report command reads this same file.

Changes

Coverage Output Correction

Layer / File(s)	Summary
Unify coverage profile output hack/unit-test.sh	The coverage script writes the mode line and merged profile data to ./_output/coverage/coverage.out and runs go tool cover -func against that file.

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

Merge Risk: ⚪ Minimal · up to 207ef

This localized change makes the coverage header and merged data use the same truncated file, correcting coverage reporting without affecting production behavior. No actionable merge-blocking risk remains beyond normal checks and review.

Suggested reviewers: archlitchi, fouof

Poem

A rabbit found one coverage file,
With header and data in a tidy pile.
The report now reads the same path,
No repeated lines remain in its math.
Hop, hop—the tests show their style!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main coverage file handling fix.
Linked Issues check	✅ Passed	The changes satisfy issue #2933 by writing the coverage mode header and merged data to ./_output/coverage/coverage.out, truncating before writing, and using that file for go tool cover. The changes al…
Out of Scope Changes check	✅ Passed	The changes are limited to hack/unit-test.sh and directly support the coverage tooling requirements in issue #2933. No unrelated production, device, or CI workflow changes are present.
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…

Full details: Linked Issues check

Explanation

The changes satisfy issue #2933 by writing the coverage mode header and merged data to ./_output/coverage/coverage.out, truncating before writing, and using that file for go tool cover. The changes also avoid CI and production code changes.

Full details: Docstring Coverage

Explanation

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 files.

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Flag	Coverage Δ
unittests	70.33% <ø> (ø)

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