Surviving a legacy codebase: tactics and tools to keep the right path We will show you how to regain control of a legacy codebase written in Java. This codebase (https://github.com/xpepper/fifty-shades-of-legacy-goose-game/tree/master/goose-game-two) shows some classic design problems but more than that, badly expresses the domain of the problem we want to solve. During the session we will tackle the code the XP way: it will be a live refactoring in pair programming; we will show how the quality and expressiveness of the code can be progressively improved if we apply some good development practices with the help of some effective tools. Made by Paolo D'Incau and Pietro Di Bello

1. Surviving to a legacy codebase
How we take back control of legacy
codebases

2. Pietro Di Bello
@pierodibello
Paolo D’Incau
@pdincau

3. What is legacy code? 🤔

4. “Code without tests.” 🤠
Michael Feathers

5. “Valuable code that we feel afraid
to change.” 💰
J.B. Rainsberger

6. Welcome to Board Games Sagl…

7. Surviving principle #1: understand
the context of your software 🔦

8. Go talk with the business

9. The business of Board Game Sagl
know that…

10. Users complain about a bug and we
are losing customers and
reputation! 💸

11. In a few weeks one of our
key gaming policies will change…

12. Let’s open the project and start
gaining confidence

13. Surviving principle #2: maximize
safety ⛑

14. Move carefully and take tiny steps

15. Remember to keep the focus on
what matters 👁

16. Remember the boy scout rule #1

17. Reduce the cognitive load 🤯

18. Slowly expand your sphere of
control on the codebase

19. Surviving principle #3: focus on the
flow of the money 💶

20. Surviving principle #4: follow the
flow of the bugs 🐛

21. To summarise…

22. “The journey of a thousand miles
begins with one step.”
Lao Tzu

23. Refactoring should be driven by real
and emergent needs

24. www.xpeppers.com
/xpepperssrl@xpeppers

25. Have fun with the Goose Game:
https://github.com/xpepper/fifty-shades-
of-legacy-goose-game/