Add GitHub file links with line numbers to Slack messages

[bashu-shopify]

human tldr: I wanted line numbers in our slack messages. This adds it.

Potentially this also adds github links, but I saw the comment here and it's possible that this won't work- tests seem to be fine but I'd like somebody who understands the issue better to weigh in on this code

The rest is summarised by Claude, seems good and i babysat him for this, read all code with my own human eyeballs etc.

Summary

This PR enhances Slack notifications to include clickable GitHub links with line numbers, making TODO notifications more actionable.

Fixes #66

Changes:

• ✨ Added line number tracking to TODO objects during comment parsing
• ✨ Created GitUtils module to detect GitHub repositories and generate file links
• ✨ Enhanced Slack messages with clickable GitHub links (e.g., https://github.com/Shopify/smart_todo/blob/main/file.rb#L42)
• ✨ Added readable fallback for non-git environments (e.g., "on line 42" instead of ":42")
• ✅ Added comprehensive test coverage (192 tests, 442 assertions, all passing)
• 🔧 Fixed git detection to work from any directory (addresses concern from Optionally include repository name in notifications #94)

Examples

With GitHub repository:

You have an assigned TODO at <https://github.com/Shopify/smart_todo/blob/main/file.rb#L42|file.rb:42> in repository `smart_todo`.

Creates a clickable link in Slack that navigates directly to the line in GitHub

Without GitHub repository:

You have an assigned TODO in the `example.rb` file on line 42 in repository `my_project`.

Falls back to human-readable line reference

Key Technical Improvement

Git Repository Detection Fix

The PR includes an important fix for how git repositories are detected. Previously, the code would use Dir.pwd (the current working directory) to look for .git, which could fail when:

• Running smart_todo from a parent directory
• Running in CI with non-standard working directories
• Passing absolute file paths

Solution: The new find_git_root method walks up the directory tree from the actual file being processed to find the .git directory. This ensures correct behavior regardless of where the command is run from.

This addresses the concern raised in #94 (comment) about base_path potentially being incorrect.

Test Coverage

Updated Tests

• OutputTest#test_dispatch_with_github_link - Verifies GitHub links in git repos
• OutputTest#test_dispatch_without_github_link - Verifies readable fallback format

New Tests (GitUtilsTest)

• ✅ HTTPS and SSH GitHub URL parsing
• ✅ Non-GitHub repository handling (GitLab, etc.)
• ✅ Branch detection and link generation
• ✅ Absolute vs relative path handling
• ✅ Edge cases (no git repo, non-GitHub remotes)
• ✅ find_git_root walking up directory tree from files/subdirectories
• ✅ Caching behavior for performance

All tests passing: 192 runs, 442 assertions, 0 failures

Performance

The implementation includes caching for git repository information:

• git_root_cache - Caches git root lookups per directory
• git_info_cache - Caches GitHub repository info

This ensures efficient operation even when processing hundreds of files, as each directory is only scanned once.

🤖 Generated with Claude Code

[Edouard-chin]

Sorry about the delay, I hadn't seen this Pull Request 😢 . Thanks for your work on this feature, it's very useful.

I reviewed #120 which implement the same feature but relies on CI providers environment variables to get git information (such as the repo/commit ...).

I think it's less brittle than reading git files as they may not even exists. (Some CI setup, ours included download a tarball rathen than cloning as its much faster).

Your review on #120 would be helpful as you have context.

Thanks !