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Coding Dojo: Adding Tests to Legacy Code (2014)
Peter Kofler led a coding dojo on adding tests to legacy code. The dojo focused on understanding legacy code, breaking dependencies, extracting pure functions and classes, and refactoring code to be testable. Participants worked on adding tests to the "Ugly Trivia" legacy codebase, an implementation of the game Trivial Pursuit, by extracting pure functions and classes and writing tests for the extracted code.
Coding Dojo: Adding Tests to Legacy Code (2014)
- 1. Coding Dojo: Adding Teststo the Ugly Trivia Legacy Code Feb. 2014 Peter Kofler, ‘Code Cop’ @codecopkofler www.code-cop.org Copyright Peter Kofler, licensed under CC-BY.
- 2. Peter Kofler • Ph.D.(Appl. Math.) • Professional Software Developer for 14 years • “fanatic about code quality” • I help development teams PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
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- 4. Coding Dojo Mindset ● Safeplace outside work ● We are here to learn ● Need to slow down ● Focus on doing it right ● Collaborative Game PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 5. Dojo Structure ● Introduction 15' ● Coding60' ● Break ● Interim (Retrospective) 15' ● Coding 60' ● Break ● Coding 60' ● Retrospective 30' PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 6. Legacy Code Skills ● UnderstandingLegacy Code ● Breaking Dependencies ● Bringing Code Under Test ● Refactoring Mercilessly PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 7. Ugly Trivia PETER KOFLER,CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 8. Legacy Codebase “uglytrivia“ ● Getthe code https://github.com/jbrains/trivia ● An implementation of Trivial Pursuit ● http://en.wikipedia.org/wiki/Trivial_Pursuit ● players take turns to answer trivia questions ● questions are split into categories ● players collect coins for right answers PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 9. Requirements ● Choose a testingframework ● Create tests, cover all cases ● May need to extract code to do that PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 10. Don't Focus on Gettingit Done. F0cus on Doing It Perfectly.
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- 12. Extract Pure Functions ● finda piece of code that can be moved into a separate function by using “Extract Method“ ● replace all external dependencies within this function with independent parameters ● add a test for that function ● refactor the tested code as needed PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 13. Extract Class ● isolate functionalitythat somehow relates and can be separated from other behaviour ● turn isolated methods into pure functions ● extract these pure functions into a separate class ● add tests for that new class PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 14. Closing Circle ● What didyou learn today? ● What surprised you today? ● What will you do differently in the future? PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 15. Peter Kofler @codecopkofler www.code-cop.org Idea by J.B.Rainsberger @jbrains https://github.com/jbrains/trivia PETERKOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 16. CC Images ● Dojo http://www.flickr.com/photos/49715404@N00/3267627038/ ● Todoshttp://www.flickr.com/photos/kylesteeddesign/3724074594/ ● Trivia http://www.flickr.com/photos/thehoneybunny/207992667/ ● Wants you http://www.flickr.com/photos/shutter/105497713/ PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY