Phase 3: Add multi-platform testing (Linux, macOS, Windows)

[RAprogramm]

Objective

Enable cross-platform testing on Linux, macOS, and Windows to ensure compatibility and catch platform-specific bugs early.

Implementation

1. Add OS Matrix to Test Job

Extend the existing matrix strategy to include multiple operating systems:

strategy:
  fail-fast: false
  matrix:
    rust:
      - ${{ needs.msrv.outputs.version }}
      - stable
    os:
      - ubuntu-latest
      - macos-latest
      - windows-latest

2. Platform-Specific Considerations

• Path Separators: Ensure tests handle both / (Unix) and \ (Windows)
• Line Endings: CRLF (Windows) vs LF (Unix/macOS)
• File Permissions: Unix permissions don't apply on Windows
• Case Sensitivity: Windows filesystem is case-insensitive
• Symbolic Links: May require special handling on Windows

3. Conditional Steps

Add platform-specific steps if needed:

- name: Platform-specific setup (Windows)
  if: runner.os == 'Windows'
  run: # Windows-specific commands

- name: Platform-specific setup (macOS)
  if: runner.os == 'macOS'
  run: # macOS-specific commands

4. Cache Optimization

Adjust cache keys for multi-platform:

- name: Cache cargo
  uses: Swatinem/rust-cache@v2
  with:
    key: test-${{ matrix.rust }}-${{ matrix.os }}
    save-if: ${{ github.ref == 'refs/heads/main' }}

Benefits

• Platform Compatibility: Catch OS-specific bugs before users do
• Wider Audience: Confidence for users on all major platforms
• Production Ready: Enterprise-grade cross-platform support
• Early Detection: CI catches platform issues immediately

Test Plan

• Matrix configuration validated
• Tests pass on Ubuntu
• Tests pass on macOS
• Tests pass on Windows
• Cache strategy optimized for multi-OS
• No platform-specific test failures
• CI runtime remains acceptable (<5 min total)

Acceptance Criteria

• Test job runs on ubuntu-latest, macos-latest, windows-latest
• All 157 tests pass on all platforms
• Platform-specific edge cases handled
• Cache keys include OS identifier
• Workflow summary shows results per platform
• No regression in CI performance

Parent: #175