Does that legacy code beast stifle your creativity? Do you stay up late at night frightened that someone might touch *that* piece of code? Learn some practical steps on how you can slay the legacy code beasts, divide and conquer, and deliver value to your customers.

1. Taming Legacy Code Monsters

2. * Caleb * I’m here to help.

4. Last year 10Reasons yoursoftwareSucks (and the 10 practicesto fix it)

5. Building teams that engineer better software Development ∙ Team Work ∙ Process

6. back to… Taming Legacy Code Monsters

7. back to… Taming Legacy Code Monsters

8. Definition “Legacy” n. Software that I’m afraid to maintain, extend, or change it actually scares me to touch that code.

9. What’s the differencebetween an application and

10. Legacy Monster

11. Legacy Monster Processor Static Config Static Proxy Processor Settings Data Connections Rules Configurations Coupling Coupling Coupling Coupling Coupling Rules Data Coupling

12. Legacy Monster Solution contained over 68 projects. Most of which were notused. No horizontal layers. Required IIS 6 / legacy URL rewriter / 32 bit C Lib / IIS Rules export/import / Database Connections / Proper Configuration X 3 To run or test ANY part on a dev box…

13. Strategy #1 Know your Foe

14. Strategy #1 nDepend

15. Strategy #1 Visual Studio Dependency Graph

16. Strategy #1 Demo Using theVisual Studio Dependency Graph

17. Strategy #1 Demo Pro tip:Look for big blobs& thick linesto concrete types

18. Strategy #2 Create aSafety Net

19. Source Control+ Test Strategy #2

20. Strategy #2 Source Control+ Test

21. Strategy #2 Source Control

22. // source // svn / git / tfs .. // r1.1 // r1 // r2 // r3 // trunk // trunk Branching for FUN! //

23. Strategy #2 Unit TestsIntegration Regression Load Tests Etc… Tests

24. Isolation and White box Unit Testing for .NET Demo: Safety Net Legacy Monster “Pexautomatically generates test suites with high code coverage.…[and] finds interesting input-output values of your methods, which you can save as a small test suite with high code coverage. Microsoft Pex is a Visual Studio add-in for testing .NET Framework applications.” Processor Static Config Static IProxy Processor Settings Data Connections Rules Configurations http://research.microsoft.com/en-us/projects/pex/ Rules Data

25. what about hard to test code? refactoring testability

26. privateIList<Bean> goodBeans { get; set;} privateIList<Bean> badBeans { get; set;} publicvoidAddBean(Bean bean){ if(bean.size > 10) goodBeans.Add(bean); else badBeans.Add(bean); } publicvoidUpdateBeans(){ BeanData.Update(goodBeans); goodBeans.Clear(); badBeans.Clear(); }

27. 1 Clearly an arbitrary example Does represent actual production code that I have worked with 2 3 AddBean(b); AddBean(b), UpdateBeans(); Usage scenario is How can we test the AddBean() Logic?

28. publicIList<Bean> GoodBeans{ get; private set;} privateIlist <Bean>badBeans{ get; set;} publicvoidAddBean(Bean bean){ if(bean.size > 10) GoodBeans.Add(bean); else badBeans.Add(bean); } publicvoidUpdateBeans(){ BeanData.Update(goodBeans); GoodBeans.Clear(); badBeans.Clear(); } privateIList<Bean> goodBeans { get; set;} privateIList<Bean> badBeans { get; set;} publicvoidAddBean(Bean bean){ if(bean.size > 10) goodBeans.Add(bean); else badBeans.Add(bean); } publicvoidUpdateBeans(){ BeanData.Update(goodBeans); goodBeans.Clear(); badBeans.Clear(); } A: create a readonlyaccessor to “sense” thegoodBean state externally

29. What about the UpdateBeans() method? publicvoidUpdateBeans(){ BeanData.Update(goodBeans); goodBeans.Clear(); badBeans.Clear(); } publicvoidUpdateBeans(){ BeanData.Update(goodBeans); goodBeans.Clear(); badBeans.Clear(); if (OnBeansUpdate != null) OnBeansUpdate(); } publiceventActionOnBeansUpdate;

30. Code Coverage + Continuous Integration Not a silver bullet still need to make sure that we are testing “the right” things, and not just hitting some magical number still need to make sure we have healthy tests Pro tip

31. Code Coverage + Continuous Integration Creates a base line or smoke test to look for Watch trends over magic percent numbers Pro tip

32. Code Coverage + Continuous Integration Team City Code Coverage

33. Code Coverage + Continuous Integration Sonar

34. Strategy #3

35. Strategy #3 Divide and Conquer (pick your battles)

36. 36 Commitment

37. 37 Raise your hand and repeat after me, Commitment

38. 38 Raise your hand and repeat after me, Commitment I will not practice bad code.

40. “Resist Legacy Coupling”

41. “Resist Legacy Coupling” tight coupling = change anywhereaffects everything Legacy Monster Processor Static Config Static Proxy Processor Settings Data Connections Rules Configurations New Functionality Coupling Needs IProxy Coupling static Config class leads to Heavy Weight testing Coupling Coupling Coupling Rules Data don’t reference Config Monster Coupling use DI for only what you need (IProxy)

42. Introduce SOLID principals on new development… gradually improve code over time http://developingux.com/di/

43. wrap up

44. Know your Foe wrap up Use a Safety Net Divide and Conquer

45. Thank you! Proaction MentorS @calebjenkins http://developingux.com @proactionmentor caleb@proactionmentors.com

46. Photo Credits © Michael Cummings - http://dreaminpictures.com http://www.flickr.com/photos/boogeyman13/2432667459/ http://www.flickr.com/photos/stopthegears/50553611/ http://www.flickr.com/photos/pochateca/324414459 http://www.flickr.com/photos/27620885@N02/2594362917

47. http://www.flickr.com/photos/27620885@N02/2594363003 http://www.flickr.com/photos/flyingturtle/3976070342/ http://www.flickr.com/photos/jfravel/1001472806/ http://www.flickr.com/photos/flyingturtle/3976076272/ http://www.lostechies.com/blogs/derickbailey/archive/2009/02/11/solid-development-principles-in-motivational-pictures.aspx