Add comprehensive testing for TLS package

[blink-so-v1]

This PR adds comprehensive testing for the TLS package, ensuring robust certificate management and SSL/TLS functionality.

📊 Coverage Improvement

Adds full test coverage for the TLS package including certificate generation, management, and configuration.

🧪 Key Improvements

Configuration Validation

• ✅ Valid configurations with all required components
• ✅ Error handling for invalid configurations (empty config dir)
• ✅ Nil logger detection and proper panic handling
• ✅ Temporary directory management for testing

Certificate Authority (CA) Management

• ✅ CA certificate and private key generation
• ✅ CA certificate persistence and loading
• ✅ PEM encoding/decoding validation
• ✅ X.509 certificate parsing and validation
• ✅ CA certificate reuse across instances

Server Certificate Generation

• ✅ Dynamic certificate generation for various hostname types
• ✅ Support for domain names (example.com)
• ✅ Support for IP addresses (192.168.1.1)
• ✅ Support for localhost
• ✅ Support for wildcard domains (*.example.com)
• ✅ Empty hostname handling
• ✅ Certificate validity period validation
• ✅ Key usage and extension validation

TLS Configuration

• ✅ TLS config setup with dynamic certificate generation
• ✅ GetCertificate callback function implementation
• ✅ Certificate caching and retrieval
• ✅ ClientHelloInfo processing
• ✅ Subject Alternative Names (SAN) handling

Interface Compliance

• ✅ Manager interface implementation verification
• ✅ SetupTLSAndWriteCACert method testing
• ✅ Return value validation (TLS config, cert paths, config dir)
• ✅ File system operations (CA cert file creation)

Integration Testing

• ✅ End-to-end certificate generation flow
• ✅ Multiple hostname certificate generation
• ✅ TLS handshake simulation with ClientHelloInfo
• ✅ Certificate validation against hostnames
• ✅ Real filesystem operations with temporary directories

🔧 Technical Excellence

Certificate Management

• Comprehensive testing of CA certificate lifecycle
• Server certificate generation with proper extensions
• Certificate caching behavior validation
• X.509 certificate parsing and validation

Error Handling

• Graceful handling of configuration errors
• Proper panic detection for nil logger
• File system error handling
• Certificate parsing error handling

Test Quality

• Table-driven tests for comprehensive coverage
• Proper temporary directory cleanup
• Real certificate generation and validation
• Performance benchmarks for critical operations

File System Operations

• CA certificate file persistence
• PEM encoding format validation
• Directory creation and ownership handling
• Cross-platform compatibility

🚀 Benefits

1. Security: Certificate generation and management thoroughly tested
2. Reliability: TLS functionality validated with real certificates
3. Maintainability: Clear test structure enables safe SSL/TLS changes
4. Performance: Benchmarks provide insights into certificate generation costs
5. Quality Assurance: Edge cases and error conditions fully covered

All tests pass successfully with proper handling of file system permissions and temporary directory management.

Co-authored-by: f0ssel [email protected]