Code Review: actions/cache v4 → v5 Update

Summary

This PR updates the actions/cache action from v4 to v5 in the CI workflow. The change is minimal and focused, affecting only 2 instances in the main dotnet.yml workflow.

✅ Positive Findings

1. Scope: The update is properly scoped - only updates actions/cache references without touching unrelated code
2. Consistency: Both cache instances (NuGet packages and Playwright browsers) are updated together, maintaining consistency
3. Configuration Preservation: The cache configuration (paths, keys, restore-keys) remains unchanged, which is correct
4. No Breaking Changes: The actions/cache@v5 API is backward compatible with v4 - no configuration changes are required
5. Standard Dependency Update: This is a typical Renovate bot update following best practices

🔍 Analysis

What changed:

• Line 57: actions/cache@v4 → actions/cache@v5 (NuGet cache)
• Line 72: actions/cache@v4 → actions/cache@v5 (Playwright cache)

Why this is safe:

• actions/cache v5 is a major version bump, but maintains backward compatibility
• The cache key format and restore-keys logic remain valid
• The cache paths are OS-agnostic and correctly use matrix variables
• The conditional logic for Playwright installation (cache-hit output) remains functional

TUnit-specific considerations:

• ✅ No dual-mode implementation required (infrastructure change only)
• ✅ No snapshot tests affected
• ✅ No performance impact (potential improvement from v5 optimizations)
• ✅ No AOT/trimming implications
• ✅ Follows TUnit's modern approach to tooling

📋 Checklist Review

• ✅ Code quality: Clean, minimal change
• ✅ Potential bugs: None identified
• ✅ Performance: No regression expected (v5 may improve cache performance)
• ✅ Security: No security concerns (official GitHub action)
• ✅ Test coverage: N/A (infrastructure change, will be validated by CI runs)

🎯 Recommendation

APPROVED ✓

This is a straightforward dependency update that:

• Follows semantic versioning properly
• Maintains existing functionality
• Uses the latest stable version of a critical CI action
• Has automerge enabled (appropriate for this type of change)

The CI pipeline will validate that caching continues to work correctly across all three OS matrices (ubuntu-latest, windows-latest, macos-latest).

Review performed in accordance with TUnit development guidelines (CLAUDE.md)