TDD A Driven Approach To Development

Transcription

1 TDD A Driven Approach To Development Tjakko Kleinhuis 3 December, 2012

2 Who? Tjakko Kleinhuis Enabler Mechanical engineer Software engineer

3 Who s still doing agile these days? How s Agile? Agile is so 2006!

4 It is pulp. Programming, Motherfucker Do you speak it? We are a community of motherfucking programmers who have been humiliated by software development methodologies for years. We are tired of XP, Scrum, Kanban, Waterfall, Software Craftsmanship (aka XP-Lite) and anything else getting in the way of...

5 It can become fiction. They Claim To Value They Really Value We **cking Do Individuals and interactions Tons of billable hours Programming, Motherf***r Working software Tons of pointless tests Programming, Motherf***r Customer collaboration Bleeding clients dry Programming, Motherf***r Responding to change Instability and plausible deniability Programming, Motherf***r

6 We re forgetting.

7 XP Values / Agile Manifesto Communication Individuals and interactions over processes and tools Simplicity Working software over comprehensive documentation Feedback Customer collaboration over contract negotiation Courage Responding to change over following a plan

8 Back to the why! Communication Talk to others in their language. Simplicity A (working) product. That s all they want. Feedback Get feedback. Make it concrete. Test & show. Courage Think, but start moving asap to get your feedback, and please, keep moving for your product.

9 Humanity Economics Mutual Benefit Self-Similarity Improvement Diversity Reflection Flow Opportunity Redundancy Failure Quality Baby Steps Accepted Responsibility XP Principles

10 Change your way of thinking

11 Change your way of thinking

12 TDD under the agile umbrella XP (developers) SCRUM (project management) Continuous Design Test-Driven Development Refactoring Continuous Integration Every change is built and tested Open source tools: CruiseControl

13 Traditional V-model Requirements Does software match specs? Acceptance Tests Architecture Quality of Design? Integration Tests Design Component Tests Random code tests Code Unit Tests TEST AFTERWARDS

14 Agile V-model Acceptance Test Communication, Predictability Right Software Feedback Continuous Integration Integration Tests Simplicity & Feedback Unit Tests Lean & Clean code TEST FIRST

15 Exam metaphore

16 TDD RHYTHM

17 Baby Steps

18 Fail FIRST

19 Dreams

20 AND Nightmares

21 Do s and don ts DO The BIG Why? Stop on pass Shortest route Baby steps Fail first! Dreams AND nightmares DON T Feature creep Over-detail Steam ahead (False!) pass first Dreams only

22 ISOLATION Seams Fakes (Stubs & Mocks) Interaction vs. state-based testing

23 Seams

24 Stubs

25 Mocks

26 Isolating an object with dependencies

27 State-based testing

28 Interaction-based testing

29 Show me: mocks

30 Show me: mocks // setup mock = new Mock (motordevice); button.attachmotor(mock); // some stubbing mock.return(startmotor).value(true); // expectations mock.expect( startmotor ).once(); // trigger button.pressed();

31 IN THE REAL WORLD New software Size matters Bug fixing Legacy code Test data (Programming) Languages

32 TDD Pitfall

33 TDD Pitfall

34 Granularity

35 Equal growth

36 Prioritize?

37 Sort, don t prioritize 1 2 3

38 Size matters The right size for a unit test Black box tests too little, often hard Avoid heavy maintenance: overdone white box Open box: test your well-evolved interface!

39 Traditional Bug Fixing

40 TDD Bug Fixing

41 Legacy Code Legacy code = technical debt don't know what it does fear that change will break it

42 Rhythm for insight

43 Sprouting

44 Sprouting

45 Sprouting

46 Test data Real data Fixtures

47 Real data

48 Fixtures

49 Fixtures Known data a fixture contains all the things that must be in place in order to run a set of tests and expect a particular outcome Typical setup() and teardown() Repeatable tests

50 Languages Java (JUnit) C++ (CPPUnit) C# (NUnit) C (CUnit) JMock (a.o.) mockpp, hippo, google Rhino See C++

51

52 REFERENCES & CREDITS

53 Recommended books Working effectively with Legacy Code Michael Feathers TDD by Example Kent Beck

54 For further reading extreme Programming explained Kent Beck The pragmatic programmer Andrew Hunt & David Thomas Growing OO software, guided by tests Steve Freeman & Nat Pryce

55 Related subjects Continuous integration Test Automation xunit testing

56 Credits Dirty Jobs Rob Westgeest a.o. (QWAN) Brain images Dorothy Graham

57 Sioux 2012 Confidential 57