This is the slides of my talk about test-driven development and continuous integration on 2011/06/11

1. Test-Driven Development
&
Continuous Integration
Hao-Cheng Lee
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2. About me
● Hao-Cheng Lee
● Java Engineer for 7+ years
● Quality Engineer@Yahoo (till yesterday ;-))
● Interested in Java, Scala, TDD, CI
● email: haocheng.lee@gmail.com
● twitter: https://twitter.com/#!/haocheng

3. Agenda
● What is TDD?
● Why use TDD?
● How to do TDD?
● What is CI?
● Why use CI?
● TDD + CI

4. TDD
=
TFD
+
Refactoring

6. Not about
writing tests...

7. TDD is about
writing better
code

8. from http://ch.englishbaby.com/forum/LifeTalk/thread/441379

9. Test Myths

10. I have no time
for testing

11. Technical Debt
from http://www.freedebtadvice-uk.com/

12. My code is
BUG-FREE!

13. from http://vincentshy.pixnet.net/blog/post/5397455

14. QA will do the
testing

15. Black Box Testing
from http://www.jasonser.com/marketing-black-box/

16. http://www.ocoee.org/Departments/HR/

17. Faster
from http://cllctr.com/view/c2fdb4d2625e109069c843ea1bb99e50

18. from Test Driven Development Tutorial by Kirrily Robert

19. Faster
● Shorter release cycle
● Automation saves time
● Find bugs earlier

20. Better
from http://www.nataliedee.com/archives/2005/sep/

21. Better
● Greater code coverage
● The courage to refactor
● Prevent regression bugs
● Improve your design

22. "I'm not a great programmer;
I'm just a good programmer
with great habits."
- Kent Beck

23. Testing the Old Way

24. TDD

25. TDD

26. How to do TDD?
● Design: figure out what you want to do
● Test: write a test to express the design
○ It should FAIL
● Implement: write the code
● Test again
○ It should PASS

27. Design
We need a method add(), which
takes two parameters and add
them together, then it will return
the result.

28. Test

29. FAIL
java.lang.AssertionError: expected:<2> but was:<0>
...
at tw.idv.haocheng.play.
CalculatorTest.one_plus_one_is_two
(CalculatorTest.java:20)

30. Implement

31. PASS

32. Write the least code
to make the test pass

33. More Test

34. FAIL
java.lang.AssertionError: expected:<4> but was:<2>
...
at tw.idv.haocheng.play.
CalculatorTest.two_plus_two_is_four
(CalculatorTest.java:25)

35. Implement

36. PASS

37. Design
The add() method only accept
positive numbers

38. Test

39. FAIL
java.lang.AssertionError: IllegalArgumentException expected
at org.junit.Assert.fail(Assert.java:91)
at tw.idv.haocheng.play.
CalculatorTest.negative_numbers_will_throw_exception
(CalculatorTest.java:32)

40. Implement

41. PASS

42. Unit Test Frameworks
● Java - JUni
● Python - PyUnit
● PHP - PHPUnit
● Ruby - Test:Unit
● Javascript - Jasmine
● .Net - NUnit

43. Good Test
● One test per scenario
● Test in isolation
● Readability
● Minimum Test Fixture
● Repeatable

44. Bad Smell
● NO Assert/Meaningless Assert
● High maintenance cost
● Interacting Tests
● Require manual debugging
● Evil Singleton

45. When is enough enough?
● One Test per class
● Testing the feature
● Find bugs, add tests
● Skip Getter/Setter if generated
● Skip Private methods
● Code coverage

46. There's No Silver Bullet
from http://www.penn-olson.com/2009/12/22/social-media-the-silver-bullet/

47. It takes time...
from http://chunkeat626.blogspot.com/2010_11_01_archive.html

48. Need to
maintain tests

49. TDD is not suitable for...
from http://www.flickr.com/photos/ilike/2443295369/

50. from http://tw.gamelet.com/game.do?code=heroes

51. from http://dilbert.com/

52. Continuous
Integration

53. Continuous Integration is a software
development practice where members
of a team integrate their work
frequently, usually each person
integrates at least daily – leading to
multiple integrations per day.
-- Martin Fowler

54. Why CI?
● Rapid Feedback
● Reduced Risk
● Collective Ownership
● Continuous Deployment
● Offload from people

55. Why TDD + CI?

56. Effective tests
must be automated
from http://www.laurentbrouat.com/why-you-should-stop-sending-auto-dms/automated/

57. Write once, run often
● Write tests once
● Run frequently
● No human input
● Common output

58. Best Practices of CI
● Single Source Repository
● Commit often
● Make Your Build Self-Testing
● Automate the Build
● Build fast

59. Extensible continuous integration
server

60. What is Jenkins?
● Open-source CI server
● Easy to install and use
● Extensibility

61. Why Jenkins?
● GUI to manage
● Strong community and eco-system
● Distributed builds
● Open Source and Free!

62. mailing list subscription is increasing

63. GitHub members is also increasing

64. Basic Features
● Notice a change
● Check out source code
● Execute builds/tests
● Record and publish results
● Notify developers

65. CI Overview
from Continuous integration with Hudson

66. Notice a change
● Build Periodically
● Depend on other projects
● Poll SCM
○ Subversion Push vs. Pull

67. Check out source code
● Subversion
● CVS
● Git
● Mercurial
● Perforce

68. Execute builds/tests
● Java
○ Ant, Maven, Gradle
● .Net
○ MSBuild, PowerShell
● Shell Script
○ Python, Ruby, Groovy

69. Record and publish results
● JUnit
● TestNG
● Findbugs
● Cobertura
● Checkstyle
● PMD

70. Job Status
Job State: Job Stability:

71. Findbugs Integration

72. Cobertura Integration

73. Project Relationship

74. Notify developers
● Twitter
● email
● RSS
● IM
● IDE
● Android/iPhone
● Firefox

76. Twitter

77. Jenkins on Eclipse
Update Site: http://code.google.com/p/hudson-eclipse/

78. Jenkins on Android
● Android Market
● Jenkins Wiki

79. eXtreme Feedback Panel plugin

80. Jenkins Sound plugin
http://wiki.jenkins-ci.org/display/JENKINS/Jenkins+Sounds+plugin

81. Installation&Upgrade
● Download Tomcat 7
● Download latest jenkins.war
● Put jenkins.war under webapps
● Start Tomcat

82. Create a Job

83. Configure a Job

84. Configure Jenkins

85. Manage Plugins

86. Jenkins for non-Java Projects
● Python
● PHP
● Ruby
● .Net

88. Reading List
● The Bowling Game Kata
● Unit Testing Guidelines
● Why are we embarrassed to admit that we don’t know how
to write tests? (中譯版本)
● "The Clean Code Talks -- Unit Testing"
● Top 10 things which make your code hard to test

89. References - Test-Driven Development
● Test Driven Development Tutorial by Kirrily Robert
● Engineer Notebook: An Extreme Programming Episode by
Robert C. Martin and Robert S. Koss
● Technical Debt by Martin Fowler
● InfoQ: Testing Misconceptions by Liam O'Connor
● Unit Test Isolation
● Erratic Test
● Singletons are Evil
● RSpec 讓你愛上寫測試

90. References - Continuous Integration
● Jenkins: http://jenkins-ci.org/
● Mailing List: http://groups.google.com/group/jenkinsci-
users
● Wiki: http://wiki.jenkins-ci.org/
● Follow @jenkinsci on Twitter
● Continous Integration by Martin Fowler
● Continuous Integration with Hudson - the book
● Continuous Integration with Hudson on JavaWorld