The Mikado Method: How to deal with complex code changes

Transcript

1. How people build software ! " The Mikado Method How to deal with complex code changes
2. How people build software ! Jakob Class Application Engineer
 
 ! github.com/mikrobi 2 $
3. How people build software ! "
4. How people build software ! ! Repairing the dashboard lights of a 69’ Pontiac 4 EASY, JUST REPLACE THE BROKEN LIGHT BULBS! … RIGHT?
5. How people build software ! ! 2 days later… 5
6. How people build software ! 6 USUALLY IT’S MORE COMPLEX THAN YOU’VE PLANNED!
7. How people build software ! ! How we play Mikado 7 • Take a look at the whole cluster • Remove the sticks one by one • Goal: Remove the emperor stick • Don’t touch any other sticks
8. How people build software ! • Change components one by one ! How we play refactoring 8 • Goal: Change this component • Don’t touch any other parts • Take a look at the whole system
9. How people build software ! • Change components one by one ! How we play refactoring 9 • Goal: Change this component • Don’t touch any other parts • Take a look at the whole system
10. How people build software ! ! What to touch first? 10 The Mikado Method
 Ola Ellnestam and Daniel Brolund https://www.manning.com/books/the-mikado-method
11. How people build software ! ! What to touch first? 11 1. Set a goal 2. Experiment • Naively implement the goal 3. Visualize what broke • Write down sub-goals 4. Revert experiment 5. Pick a sub-goal and repeat 2.
12. How people build software ! ! 2016: Timeline for user profiles 12 • Go back in time • New activity events • Joined GitHub • First repository • First Issue • First pull request
13. How people build software ! ! The history of contributions 13 250 500 2012 2013 2014 2015 Lines of code Lines of test code Comlexity
14. How people build software ! ! Step 1: Set a goal 14 DEFINE A STARTING POINT AND AN ENDPOINT. Profiles only show the activity of the last month. 
 % Viewer should be able to browse the whole history.
15. How people build software ! ! Step 2: Experiment 15 MAKE A SIMPLE CHANGE AND SEE WHAT BREAKS.
16. How people build software ! ! Step 3: Visualize 16 CREATE A DEPENDENCY GRAPH OF STEPS REQUIRED TO REACH THE GOAL. Add timeline to profile Add :to parameter to calendar class Pass :to parameter in XYZ …
17. How people build software ! ! Step 4: Revert 17 RESTORE THE WORKING STATE AFTER EVERY EXPERIMENT. > git checkout master
18. How people build software ! ! How to reach the goal? 18 • Repeat the steps for every “failed” experiment • Append requirements to the dependency graph • Revert changes • Commit changes once experiment does not break anything • Work all the way through the dependency graph
19. How people build software ! ! Example of a dependency graph 19
20. How people build software ! ! Benefits 20 • System is always in a stable state Goal Requirement … … & & • Graph documents progress • Enables collaboration • Light weight process
21. How people build software ! ! Challenges 21 • So-close syndrome • Revert changes, don’t get trapped! • Ruby is dynamically typed • Rely on tests • Bad test coverage • Add missing tests • Manual testing
22. How people build software ! " LET’S PLAY! QUESTIONS?