fix(template): explain missing GTest for module tests

[tbirdso]

Background

Internal user reported behavior where missing GTest failed a default C++ native build

Investigation and Update

This behavior is intentional with "_BUILD_TESTS:BOOL=ON" by default. Keep the tests on-by-default and better document the flag to disable.

Results

Local end-to-end test verified error reporting, default testing behavior.

Assisted-by: Codex:GPT-5

Summary by CodeRabbit

• Documentation
  • Clarified when module tests are enabled by default and how to disable them.
  • Documented that C++ tests require GTest and that BUILD_TESTING=OFF does not disable module tests.
• Bug Fixes
  • C++ project configuration now displays a clear error when tests are enabled but GTest is unavailable.
• Tests
  • Added checks for C++ project configuration with testing disabled, GTest available, and GTest unavailable.

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⚙️ Run configuration

Configuration used: Organization UI

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Run ID: 3af9f326-d851-4775-935e-f4c411a539e7

📥 Commits

Reviewing files that changed from the base of the PR and between 2389754 and 496537f.

📒 Files selected for processing (4)

• src/holoscan_cli/templates/module/{{cookiecutter.module_repo_name}}/DEVELOPER.md
• src/holoscan_cli/templates/module/{{cookiecutter.module_repo_name}}/README.md
• src/holoscan_cli/templates/module/{{cookiecutter.module_repo_name}}/tests/cpp/{% if cookiecutter.language == 'cpp' %}CMakeLists.txt{% endif %}
• tests/unit/test_module_template.py

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Walkthrough

The module template now documents its test option and C++ GTest requirements. CMake reports a targeted error when tests are enabled and GTest is unavailable. A parameterized test checks configuration with tests disabled, GTest available, and GTest unavailable.

Changes

Module test configuration

Layer / File(s)	Summary
Test option and GTest configuration src/holoscan_cli/templates/module/{{cookiecutter.module_repo_name}}/DEVELOPER.md, src/holoscan_cli/templates/module/{{cookiecutter.module_repo_name}}/README.md, src/holoscan_cli/templates/module/{{cookiecutter.module_repo_name}}/tests/cpp/{% if cookiecutter.language == 'cpp' %}CMakeLists.txt{% endif %}, tests/unit/test_module_template.py	The documentation describes the module test option’s defaults, how to disable tests, and the GTest requirement for C++ tests. CMake reports an error with guidance when GTest is missing. Tests cover configuration with tests disabled, GTest available, and GTest unavailable.

Priority: ⬇️ Low

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

Merge Risk: ⚪ Minimal · up to 49653

The change documents how to disable module tests and provides a targeted error when GTest is missing. It is ready for normal merge checks.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 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 change: documenting the missing GTest requirement for module tests in the template.
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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[wyli]

Reviewed the GTest discovery change and generated documentation. The existing test defaults are preserved, and the missing-dependency error provides the correct module-scoped opt-out. All 17 targeted template/scaffolding tests passed locally, and the current CI checks are green.