Derek Neighbors

The more I learn, the less I know.

Agile Revitalizing Legacy Code: 5 Steps to Successful Refactoring

By Derek Neighbors, Published on March 23, 2023

Legacy code can be a daunting challenge for any developer. It’s that spaghetti code that nobody wants to touch. But don’t despair! Legacy code is not only an opportunity for growth and learning, but it’s also a valuable skill to have as a software engineer.

What Is Legacy Code

According to Michael Feathers (@mfeathers), author of the book “Working Effectively with Legacy Code”, legacy code is “code without tests”. It’s code that’s been around for a while, often poorly documented, and has been hacked on and patched over the years. It’s the code that nobody wants to touch because they’re afraid of breaking something.

Knowing When to Rewrite Vs Improve Legacy Code

Martin Fowler(@martinfowler), author of “Refactoring: Improving the Design of Existing Code”, suggests that you should only rewrite code when you have a clear understanding of what the code does and what you want it to do. If you don’t understand the code, you’ll likely end up introducing new bugs and creating a bigger mess. On the other hand, if you understand the code and can identify specific areas that need improvement, it’s usually best to start with small refactorings.

Is Working with Legacy Code a Valuable Skill

Kent Beck (@KentBeck), author of “Test Driven Development: By Example”, argues that legacy code is the norm in most software development organizations. It’s rare to work on a greenfield project where you can start from scratch. Learning how to work with legacy code and make it better is a valuable skill that will serve you well throughout your career.

Five Steps to Start Improving Your Legacy Code

  1. Understand the code: Spend time reading through the code and getting a sense of what it does. Use tools like static analysis and code coverage to help you get a better understanding of the codebase.
  2. Identify areas for improvement: Once you understand the code, identify specific areas that need improvement. Look for code that’s duplicated, overly complex, or hard to understand.
  3. Write tests: Before you start making changes, write tests to cover the existing functionality. This will give you confidence that your changes aren’t breaking anything.
  4. Refactor: Start with small refactorings that improve the code without changing its behavior. Refactoring is a skill that takes time to develop, but it’s worth the effort.
  5. Repeat: Keep repeating steps 1-4 until the codebase is in a better state. It’s a gradual process, but with each iteration, the code will become easier to work with.

Working with legacy code can be a challenging but rewarding experience. It’s an opportunity to learn new skills, improve your understanding of the codebase, and make a meaningful impact on the software you’re working on. Remember, don’t be afraid to dive in and start improving the code. With each step forward, you’re making the codebase better for yourself and future developers. Happy coding!