Code Quality Assurance v4 (2013)
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The document summarizes a presentation by Peter Kofler on code quality assurance. It discusses Kofler's background and tools he uses to ensure code quality, including mindset/books, code kata exercises, test-driven development, code coverage, continuous integration, static analysis, and code review. It provides an example of using test-driven development to implement a prime factors kata coding exercise.
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Code Quality Assurance v4 (2013)
- 1. Code Quality Assurance FH Technikum Wien, April 2013 Peter Kofler, ‘Code Cop’ @codecopkofler www.code-cop.org Copyright Peter Kofler, licensed under CC-BY.
- 3. Peter Kofler • Ph.D. (Appl. Math.) • Professional Software Developer for 14 years • Lead Developer at IBM • “fanatic about code quality” PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 4. The opinions expressed here are my own and do not necessarily represent those of current or past employers. PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 5. Tools of the Trade ● Mindset/Books ● Code Kata ● TDD/BDD ● Code Coverage ● CI ● Static Analysis ● Code Review PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 10. Boy Scout Rule
- 14. Craftsmanship Engineering PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 19. What Exactly Will We Do? ● write code together ● using TDD ● see techniques and patterns ● discuss while doing PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 20. The Requirements. • Write a class named “PrimeFactors” that has one static method: generate. ● The generate method takes an integer argument and returns a List<Integer>. ● That list contains the prime factors in numerical sequence. http://butunclebob.com/ArticleS.UncleBob.ThePrimeFactorsKata PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 21. First Some Math. ● Prime Number: number > 1 that has no divisors other than 1 and itself. ● e.g. 2, 3, 5, 61, 67, ..., 997, ..., 243112609 -1 ● Prime Factors: prime numbers that divide an integer without remainder. ● e.g. 2 = 2, 4 = 2 * 2, 24 = 2 * 2 * 2 * 3 288 = 25 * 32 PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 22. Requirements (for Mortals). • code a file/module/class “PrimeFactors” • function/method/routine “generate“ • accept an integer number as parameter • return the prime factors of that number PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 23. Demo(Code Kata)
- 24. Keep the bar green to keep the code clean
- 25. Unit Testing • test individual units • isolate each part • show that the individual parts are correct • regression testing • sort of living documentation • executed within a framework PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 26. PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 27. Some xUnit Frameworks ● Smalltalk – SUnit ● Java - JUnit, TestNG ● .NET - NUnit, Typemock ● C++ - CppUTest ● Groovy, PHP, Python, Ruby, Scala, ... PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 28. “I write unit tests for one reason: so my coworkers don't f*** up my code.” (David Angry)
- 29. Test-Driven Development ● add a test ● run all tests and see if the new one fails ● write some code ● run all tests and see them succeed ● refactor code mercilessly ● „Red Green Refactor“ PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 30. A minute ago all their code worked
- 33. Scenarios and Stories focus on behaviour (e.g. requirements are behaviour) full sentences expected behaviour should Use Arrange-Act-Assert in form of Given-When-Then PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 35. You have to want it
- 36. TESTING I FIND YOUR LACK OF TESTS DISTURBING.
- 38. Code Coverage comprehensiveness of tests
- 41. Some Code Coverage Tools ● Java - EMMA, Cobertura, Clover ● .NET - NCover, PartCover ● C++ - Covtool, gcov ● Ruby – rcov ● commercial products PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 42. Never measure developers by Code Coverage!
- 43. Demo(Coverage)
- 44. Coverage helps. Use it! Really, Use it!
- 45. Demo(Jenkins)
- 49. Continuous Integration • Maintain a code repository • Automate the build • Make the build self-testing • Everyone commits every day • Every commit should be built • Keep the build fast • Everyone can see the results of the build PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 51. Some CI Servers ● Java - Jenkins (Hudson), CruiseControl ● .NET - TFS, Jenkins, CruiseControl.NET ● C++ - Jenkins (Shell/Make) ● Ruby – CruiseControl.rb ● commercial products - TeamCity, ALA PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 54. Good Enough?
- 55. Demo(Warnings)
- 57. Check What? • Lexical analysis –naming, coding conventions, design idioms • Flow/path analysis –null-pointer, dead code (conditional) • Dependency analysis –architectural/design flaws • Verification –mathematical proof of correctness PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 58. Some Static Analysis Tools ● Java - Checkstyle, Findbugs, PMD ● .NET - FxCop, (ReSharper, NDepend) ● C++ - (Sp)Lint ● Ruby - Roodi, Dust, Flog, Saikuro ● commercial products PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 59. Many, Many Tools
- 60. Good Enough?
- 61. Demo(Review)
- 62. Some Code Review Tools ● Your peer (Pair Programming) ● Your version control system ● Your IDE (e.g. ReviewClipse) ● Commercial products PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 64. Lessons Learned (!) Boy Scout Rule (!) Do TDD/BDD (!) Use the Tools (Coverage, CI, Static Analysis) PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 65. Thank You PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 66. Peter Kofler @codecopkofler www.code-cop.org PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 68. Links #2 Unit Test • http://en.wikipedia.org/wiki/Unit_testing • http://en.wikipedia.org/wiki/XUnit • http://en.wikipedia.org/wiki/List_of_unit_testing_frameworks TDD • http://en.wikipedia.org/wiki/Test_Driven_Development BDD • http://en.wikipedia.org/wiki/Behavior_Driven_Development • http://dannorth.net/introducing-bdd/ • http://behaviour-driven.org/ Code Coverage ● http://en.wikipedia.org/wiki/Code_coverage ● http://www.ibm.com/developerworks/java/library/j-cq01316/ PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 69. Links #3 Continuous Integration • http://en.wikipedia.org/wiki/Continuous_integration • http://www.codinghorror.com/blog/archives/000818.html • http://www.stevemcconnell.com/ieeesoftware/bp04.htm • http://www.joelonsoftware.com/articles/fog0000000023.html • http://jenkins-ci.org/ Static Code Analysis • http://en.wikipedia.org/wiki/Static_code_analysis • http://en.wikipedia.org/wiki/List_of_tools_for_static_code_analysis Code Review ● http://en.wikipedia.org/wiki/Code_review ● http://en.wikipedia.org/wiki/Pair_programming PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 70. CC Images • spray face: http://www.flickr.com/photos/iangallagher/4115047191/ • Judge Dredd: http://www.flickr.com/photos/eldave/6169431454/ • list: http://www.flickr.com/photos/kylesteeddesign/3724074594/ • eggs: http://www.flickr.com/photos/nickwheeleroz/2475011402/ • windows: http://www.flickr.com/photos/sketchglass/4281424410/ • shoe maker: http://www.flickr.com/photos/tbatty/1450209613/ (by 2010, now dead link) • factory: http://www.flickr.com/photos/94693506@N00/4643248587/ • passion: http://gapingvoid.com/2011/03/29/suddenly-passion/ • questions: http://www.flickr.com/photos/oberazzi/318947873/ PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY
- 71. CC Images • fence: http://www.flickr.com/photos/30830597@N08/3630649274/ • Darth Vader: http://rubystammtisch.at/ • covered car: http://www.flickr.com/photos/paulk/3166328163/ • works: http://www.codinghorror.com/blog/archives/000818.html • Agnes: http://www.youbrokethebuild.com/ • microscope: http://www.flickr.com/photos/gonzales2010/8632116/ • wtf: http://www.flickr.com/photos/smitty/2245445147/ • questions: http://www.flickr.com/photos/seandreilinger/2326448445/ PETER KOFLER, CODE-COP.ORG FANATIC ABOUT CODE QUALITY