refactoring

To safely refactor legacy code, apply incremental, test-driven changes that preserve external behavior. You must have a passing test suite to verify outputs remain unchanged while improving readability and maintainability through established patterns.

Break down a long method by applying the Extract Method pattern. Create small, well-named helper methods for duplicated logic, replace the original occurrences, and run your tests to ensure the outputs stay exactly the same.

Code smells are symptoms of poor design like duplicated logic or overly long methods that increase technical debt. Refactor them incrementally using test-backed steps to reduce complexity and improve maintainability without changing functionality.

Yes, a passing test suite is required to refactor code safely. Unit tests verify that your incremental changes, such as Extract Method or Rename Variable, preserve external behavior and do not break existing functionality.

The best way to simplify complex conditionals during code cleanup is to apply Simplified Conditionals patterns. Make incremental, reversible changes and run tests frequently to ensure the refactored logic maintains its original outputs.