TDD Refactor Phase - Improve Quality & Security

Clean up code, apply security best practices, and enhance design whilst keeping all tests green and maintaining GitHub issue compliance.

GitHub Issue Integration

Issue Completion Validation

• Verify all acceptance criteria met - Cross-check implementation against GitHub issue requirements
• Update issue status - Mark issue as completed or identify remaining work
• Document design decisions - Comment on issue with architectural choices made during refactor
• Link related issues - Identify technical debt or follow-up issues created during refactoring

Quality Gates

• Definition of Done adherence - Ensure all issue checklist items are satisfied
• Security requirements - Address any security considerations mentioned in issue
• Performance criteria - Meet any performance requirements specified in issue
• Documentation updates - Update any documentation referenced in issue

Core Principles

Code Quality Improvements

• Remove duplication - Extract common code into reusable methods or classes
• Improve readability - Use intention-revealing names and clear structure aligned with issue domain
• Apply SOLID principles - Single responsibility, dependency inversion, etc.
• Simplify complexity - Break down large methods, reduce cyclomatic complexity

Security Hardening

• Input validation - Sanitise and validate all external inputs per issue security requirements
• Authentication/Authorisation - Implement proper access controls if specified in issue
• Data protection - Encrypt sensitive data, use secure connection strings
• Error handling - Avoid information disclosure through exception details
• Dependency scanning - Check for vulnerable NuGet packages
• Secrets management - Use Azure Key Vault or user secrets, never hard-code credentials
• OWASP compliance - Address security concerns mentioned in issue or related security tickets

Design Excellence

• Design patterns - Apply appropriate patterns (Repository, Factory, Strategy, etc.)
• Dependency injection - Use DI container for loose coupling
• Configuration management - Externalise settings using IOptions pattern
• Logging and monitoring - Add structured logging with Serilog for issue troubleshooting
• Performance optimisation - Use async/await, efficient collections, caching

C# Best Practices

• Nullable reference types - Enable and properly configure nullability
• Modern C# features - Use pattern matching, switch expressions, records
• Memory efficiency - Consider Span, Memory for performance-critical code
• Exception handling - Use specific exception types, avoid catching Exception

Security Checklist

• Input validation on all public methods
• SQL injection prevention (parameterised queries)
• XSS protection for web applications
• Authorisation checks on sensitive operations
• Secure configuration (no secrets in code)
• Error handling without information disclosure
• Dependency vulnerability scanning
• OWASP Top 10 considerations addressed

Execution Guidelines

1. Review issue completion - Ensure GitHub issue acceptance criteria are fully met
2. Ensure green tests - All tests must pass before refactoring
3. Confirm your plan with the user - Ensure understanding of requirements and edge cases. NEVER start making changes without user confirmation
4. Small incremental changes - Refactor in tiny steps, running tests frequently
5. Apply one improvement at a time - Focus on single refactoring technique
6. Run security analysis - Use static analysis tools (SonarQube, Checkmarx)
7. Document security decisions - Add comments for security-critical code
8. Update issue - Comment on final implementation and close issue if complete

Refactor Phase Checklist

• GitHub issue acceptance criteria fully satisfied
• Code duplication eliminated
• Names clearly express intent aligned with issue domain
• Methods have single responsibility
• Security vulnerabilities addressed per issue requirements
• Performance considerations applied
• All tests remain green
• Code coverage maintained or improved
• Issue marked as complete or follow-up issues created
• Documentation updated as specified in issue