Add Core Utility Libraries Migration with Comprehensive Bash Testing

[ooloth]

💪 What

Core Utility Libraries Migration: Complete migration of machine detection and prerequisite validation from zsh to bash, establishing the foundation for all setup processes.

Files Changed

• bin/lib/machine-detection.bash - Machine type detection with hostname patterns (13 tests, all passing)
• bin/lib/prerequisite-validation.bash - System prerequisites validation (19 tests, all passing)
• test/setup/test-machine-detection-bash.bats - Comprehensive unit tests for machine detection
• test/setup/test-prerequisite-validation-bash.bats - Comprehensive unit tests for prerequisite validation

Core Functionality Migrated

Machine Detection:

• detect_machine_type() - Hostname pattern matching (Air/Mini/Work)
• set_machine_variables() - Environment variable setup (IS_AIR, IS_MINI, IS_WORK)
• init_machine_detection() - Complete initialization with optional debug output

Prerequisite Validation:

• validate_command_line_tools() - Xcode Command Line Tools verification
• validate_network_connectivity() - Essential service reachability (GitHub, raw.githubusercontent.com)
• validate_macos_version() - Minimum version compatibility (macOS 12.0+)
• validate_directory_permissions() - Directory existence and access validation
• validate_write_permissions() - Write access verification with temp file testing
• run_prerequisite_validation() - Comprehensive validation workflow with detailed reporting

🤔 Why

Foundation for bash migration project: These utilities are used by all setup processes and needed to be migrated first to establish the core infrastructure for the bash migration.

Quality improvements:

• Industry-standard tooling - Zero shellcheck warnings for both utilities
• Comprehensive test coverage - 32 total tests covering all functions and edge cases
• Better error handling - Improved error messages and graceful fallbacks
• Architecture awareness - Environment variable overrides and debug modes

👀 Usage

Machine Detection:

source "$DOTFILES_ROOT/bin/lib/machine-detection.bash"

# Initialize machine detection
init_machine_detection

# Check machine type
if [[ "$IS_AIR" == "true" ]]; then
    echo "Running on personal MacBook Air"
elif [[ "$IS_MINI" == "true" ]]; then
    echo "Running on Mac Mini server"  
else
    echo "Running on work machine"
fi

Prerequisite Validation:

source "$DOTFILES_ROOT/bin/lib/prerequisite-validation.bash"

# Run all validation checks
if run_prerequisite_validation; then
    echo "System ready for installation"
else
    echo "Prerequisites not met, please fix issues above"
    exit 1
fi

# Individual validations
validate_command_line_tools
validate_network_connectivity
validate_macos_version

👩‍🔬 How to validate

Run all tests:

# Machine detection tests (13 tests)
./test/run-tests.zsh test-machine-detection-bash
# OR
bats test/setup/test-machine-detection-bash.bats

# Prerequisite validation tests (19 tests)  
./test/run-tests.zsh test-prerequisite-validation-bash
# OR
bats test/setup/test-prerequisite-validation-bash.bats

Test machine detection:

# Test hostname detection
MACHINE=air bin/lib/machine-detection.bash detect_machine_type
# Should output: air

# Test with debug mode
DEBUG_MACHINE_DETECTION=true bin/lib/machine-detection.bash init_machine_detection

Test prerequisite validation:

# Run validation on current system
bin/lib/prerequisite-validation.bash run_prerequisite_validation

# Test individual components
bin/lib/prerequisite-validation.bash validate_macos_version

Verify shellcheck compliance:

shellcheck bin/lib/machine-detection.bash
shellcheck bin/lib/prerequisite-validation.bash
# Both should show no warnings

All 32 tests pass, zero shellcheck warnings, maintains complete feature parity with original zsh implementations.

🔗 Related links

• Bash Migration Task Documentation - Project roadmap
• PR #17: Homebrew Utilities Migration - Previous parallel development
• Original machine-detection.zsh - Reference implementation
• Original prerequisite-validation.zsh - Reference implementation