fix util test os filenames + new GetGroupGID impl

[havetisyan]

Description

rewrite GetGroupGID using file contents directly based on GCA recommendation instead of calling grep.

Contribution Checklist:

• The pull request does not introduce any breaking changes
• I have read the contribution guidelines.
• Create an issue and link to the pull request.

Attach Screenshots (Optional)

[gemini-code-assist]

Summary of Changes

Hello @havetisyan, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly refactors the group ID retrieval mechanism within the utility package by introducing a new GetGroupGID function that directly reads and parses the /etc/group file. This change moves away from executing external grep commands, enhancing the robustness and cross-platform compatibility of the group lookup logic. Additionally, the PR includes important fixes to OS-specific test file names and expands the test suite for the updated group ID retrieval functionality, ensuring comprehensive validation of the new implementation.

Highlights

• Refactored Group ID Retrieval: The GetGroupGID function has been rewritten to directly parse the /etc/group file, eliminating the previous reliance on external grep commands. This change improves efficiency and cross-compilation compatibility by avoiding Cgo requirements.
• Updated OS-Specific Utilities: Calls to the old gidForGroup function in os_util_darwin.go, os_util_freebsd.go, and os_util_linux.go have been replaced with the new GetGroupGID implementation, and the redundant gidForGroup function has been removed from these files.
• Corrected Test Filenames: The OS-specific test files have been renamed to reflect their correct operating system targets: util_test_linux.go is now util_darwin_test.go, and util_test_darwin.go is now util_linux_test.go.
• Expanded Test Coverage: New test cases have been added for GetGroupGID to cover various scenarios, including empty and whitespace group names, special characters, common groups like 'wheel' and 'root', case sensitivity, and consistency across multiple lookups.
• Codebase Improvements: Apache license headers have been added to several utility files, and a typo in the TestValidateScriptArgumens function name was corrected to TestValidateScriptArguments.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request refactors the group ID lookup to read /etc/group directly, which is a significant improvement for cross-compilation and performance by avoiding shelling out to grep. The new GetGroupGID implementation is clean, and the test suite has been expanded to cover more edge cases. My feedback includes a suggestion to make GetGroupGID more robust by handling empty group names explicitly. Additionally, I've recommended changes to the new case-sensitivity tests to make them more effective by using assertions (t.Errorf) instead of just logging informational messages.