The document discusses refactoring legacy code for a social networking website for travelers. It describes business requirements where users must be logged in to see content and be friends to see others' trips. When refactoring production code, tests must be added first and refactoring should start from the deepest code branches and move outward. Tests should also be added from the shortest code branches outward. Tips are provided on writing clean, readable code and tests in small, safe increments with frequent commits while embracing changes.

1. Testing and Refactoring
Legacy Code
Sandro Mancuso
@sandromancuso
craftedsw.blogspot.com

2. What is this session about?

3. Business Requirements
Imagine a social networking website for
travellers
• You need to be logged in to see the content
• You need to be a friend to see someone else’s
trips

4. Legacy Code Rules
• You cannot change production code if not
covered by tests
– Just automated refactoring (via IDE) is allowed, in
case it is needed for writing a test

5. Show me the code

6. Start refactoring from
deepest to shortest
branch
Start testing from
shortest to
deepest branch
Working with Legacy Code Tips

7. Trip Service - Problems
TripService
+findTripsByUser(User) : List<Trip>
<<Singleton>>
UserSession
+getInstance() : UserSession
+getLoggedUser() : User
TripDAO
+findTripsByUser(User) : List<Trip>

8. Let’s write some code

9. Start refactoring from
deepest to shortest
branch
Start testing from
shortest to
deepest branch
Working with Legacy Code Tips

10. Craftsmen at work
• Write readable and maintainable code and tests
– Code must express business rules
• Strive for simplicity
• Know your tools well (i.e. frameworks, shortcuts)
• Work in small and safe increments
– Commit often
• Embrace changes, be brave
• Boy scout rule / No broken windows

11. Thanks
Sandro Mancuso
@sandromancuso
craftedsw.blogspot.com
https://github.com/sandromancuso/trip-service-kata
leanpub.com/socra