Refactoring

0-Agenda.md

• About me
• The world's fastest explanation of refactoring
• Some examples of refactoring from real-life applications
• Hairier examples of refactoring from real-life applications
• My refactoring algorithm
• Open mic

1-Examples.md

Redability: Capture BFF business listing

Readability again: in-tray-service OCR results handler

Remove duplication: Capture screen onboarding completion

Performance improvement: document-storage-service gathering number of attachments

What makes these examples safe?

2-More challenging examples.md

Tests verify implementation, not behaviour: Capture text fields

Excessive mocking: document-storage-service document upload endpoints

Tests that are too DRY: in-tray-service email endpoints - actual tests are here

No tests at all: Capture API client

Having tests is not enough - you need good tests to refactor with confidence.

3-Algorithm.md

So, you want to refactor some code. Here's how I do it.

• Do you really want to refactor? Measure pros and cons. Sometimes it's OK to leave it for later.
• Have a good sense of what you want to do - extract methods, create classes, apply a pattern...
  • Refactoring Guru may give you some ideas
• Make sure you understand what the code currently does
  • Tests are the best source of information
  • If the tests are heavily tied to the implementation, go cry in a corner somewhere. Then change them to verify a behaviour instead.
• Add any missing tests to ensure the current behaviour is maintained
  • What if the current behaviour is wrong?
• Apply your refactoring
• Run tests until they're all passing
• Repeat until you're satisfied with your code

9-Resources.md

• Gilded Rose Refactoring Kata
• Refactoring Guru