Poznan TDD Workshop Part 1

Transcript

1. Mobile
   Academy
   

   View Slide

2. Mobile
   Academy
   @eldudi
   #TDDPoznan
   

   View Slide

3. What is a unit test?
   @eldudi #TDDWarsaw
   

   View Slide

4. @eldudi #TDDPoznań
   “Unit testing is a method by which
   individual units of source code, sets of
   one or more computer program
   modules together with associated
   control data, usage procedures, and
   operating procedures are tested to
   determine if they are fit for use.”
   4
   Kolawa, Adam; Huizinga, Dorota (2007). Automated Defect Prevention: Best Practices in
   Software Management.
   

   View Slide

5. @eldudi #TDDPoznan
   Um… what?
   5
   

   View Slide

6. @eldudi #TDDPoznań
   “Unit testing is a method by which
   individual units of source code, sets of
   one or more computer program
   modules together with associated
   control data, usage procedures, and
   operating procedures are tested to
   determine if they are fit for use.”
   6
   Kolawa, Adam; Huizinga, Dorota (2007). Automated Defect Prevention: Best Practices in
   Software Management.
   

   View Slide

7. @eldudi #TDDPoznan
   What is an app?
   7
   

   View Slide

8. @eldudi #TDDPoznan
   An app is a set of
   behaviours created by
   programmer and
   expected by user.
   8
   

   View Slide

9. @eldudi #TDDPoznan
   We, programmers, have
   a limited cognition. As
   all humans do.
   9
   

   View Slide

10. @eldudi #TDDPoznan
    We can’t always ‘load’
    all of the code of our
    app into our memory.
    10
    

    View Slide

11. @eldudi #TDDPoznan
    This means that we can,
    by accident, change the
    behaviour of the app.
    11
    

    View Slide

12. @eldudi #TDDPoznan
    Preserving behaviour of
    complex systems is
    hard. In fact, of any
    system at all.
    12
    

    View Slide

13. @eldudi #TDDPoznan
    Enter unit tests.
    13
    

    View Slide

14. @eldudi #TDDPoznan
    Unit test is a failsafe to
    make sure app
    behaviour is preserved.
    14
    

    View Slide

15. @eldudi #TDDPoznan
    What is a unit test?
    15
    

    View Slide

16. @eldudi #TDDPoznan
    Unit tests test smallest
    parts of your code in
    isolation with test code
    16
    

    View Slide

17. @eldudi #TDDPoznan
    Unit tests test smallest
    parts of your code in
    isolation with test code
    17
    

    View Slide

18. @eldudi #TDDPoznan
    Test isolation
    18
    

    View Slide

19. @eldudi #TDDPoznań
    processOrder getDishes
    19
    Table Waiter Cook
    

    View Slide

20. @eldudi #TDDPoznań
    I’m
    a cook
    Table Waiter Cook
    processOrder
    getDishes
    Fake cook
    20
    

    View Slide

21. @eldudi #TDDPoznan
    Why isolate?
    21
    

    View Slide

22. @eldudi #TDDPoznan
    Unit test lifecycle
    22
    

    View Slide

23. @eldudi #TDDPoznań
    Unit test lifecycle
    • Arrange
    • Act
    • Assert
    23
    

    View Slide

24. @eldudi #TDDPoznan
    When a unit test is not
    a unit test?
    24
    

    View Slide

25. @eldudi #TDDPoznań
    A test is not a unit test if…
    • It talks to a database
    • It communicates across network
    • It touches the file system
    • You have to do special things to your environment
    to run it (edit config files etc)
    25
    

    View Slide

26. @eldudi #TDDPoznań
    A test is not a unit test if…
    • It talks to a database
    • It communicates across network
    • It touches the file system
    • You have to do special things to your environment
    to run it (edit config files etc)
    26
    

    View Slide

27. @eldudi #TDDPoznań
    A test is not a unit test if…
    • It talks to a database
    • It communicates across network
    • It touches the file system
    • You have to do special things to your environment
    to run it (edit config files etc)
    27
    

    View Slide

28. @eldudi #TDDPoznan
    A 100 ms tests is a
    very slow test.
    28
    

    View Slide

29. @eldudi #TDDPoznan
    1500 tests each running 100
    ms. That’s 150 seconds. Two
    and a half minutes.
    29
    

    View Slide

30. @eldudi #TDDPoznan
    Where does TDD fit in
    all this?
    30
    

    View Slide

31. @eldudi #TDDPoznan
    Test Driven
    Development
    31
    

    View Slide

32. @eldudi #TDDPoznan
    Test Driven
    Development
    32
    

    View Slide

33. @eldudi #TDDPoznan
    In TDD you always
    write test first. Always.
    33
    

    View Slide

34. @eldudi #TDDPoznan
    TDD is not “just adding
    tests first”. It’s a complete
    workflow.
    34
    

    View Slide

35. @eldudi #TDDPoznan
    TDD is a great way to
    determine how complex your
    code has become.
    You just have to listen.
    35
    

    View Slide

36. @eldudi #TDDPoznan
    Have to fake seven
    objects to isolate test?
    36
    

    View Slide

37. @eldudi #TDDPoznan
    Have to inject a fake
    into a fake into a fake?
    37
    

    View Slide

38. @eldudi #TDDPoznań
    Your test setup
    method has 70 lines?
    38
    

    View Slide

39. @eldudi #TDDPoznan
    You need to simulate five
    events to test one
    method?
    39
    

    View Slide

40. @eldudi #TDDPoznan
    This always points to an
    overcomplicated design.
    And your tests are here to point
    that out. Very clearly.
    40
    

    View Slide

41. @eldudi #TDDPoznan
    By writing the test first,
    you're forced into thinking
    what responsibilities given
    object should have.
    41
    

    View Slide

42. @eldudi #TDDPoznan
    By writing test first you’re
    becoming a consumer of
    your upcoming API.
    42
    

    View Slide

43. @eldudi #TDDPoznan
    Clarify requirements
    43
    

    View Slide

44. @eldudi #TDDPoznan
    All behaviors are testable.
    The only thing that is not
    testable is your code
    44
    

    View Slide

45. @eldudi #TDDPoznan
    What unit tests
    can’t do?
    45
    

    View Slide

46. @eldudi #TDDPoznan
    Unit tests are never a
    guarantee that you
    won’t ship a bug.
    46
    

    View Slide

47. @eldudi #TDDPoznan
    But they’re damn good at
    greatly reducing amount
    of bugs. And time spent
    on QA.
    47
    

    View Slide

48. @eldudi #TDDPoznan
    Are unit tests an invaluable tool for
    writing great software? Heck yes.
    Am I going to produce a poor product
    if I can’t unit test? Hell no.
    Jonathan Rasmusson
    48
    http://agilewarrior.wordpress.com/2012/10/06/its-not-about-the-unit-tests/
    

    View Slide

49. @eldudi #TDDPoznan
    Quick
    49
    

    View Slide

50. @eldudi #TDDWarsaw
    Quick
    BDD Testing Framework
    50
    

    View Slide

51. @eldudi #TDDPoznan
    Behavior Driven Development
    Test Driven Development
    51
    

    View Slide

52. @eldudi #TDDPoznan
    BDD aims to improve
    certain aspect of TDD
    52
    

    View Slide

53. @eldudi #TDDPoznan
    BDD tries to help you
    know what to test
    53
    

    View Slide

54. @eldudi #TDDPoznan
    When writing tests
    don’t think ‘tests’
    54
    

    View Slide

55. @eldudi #TDDPoznan
    Think about
    ‘behaviors’
    55
    

    View Slide

56. @eldudi #TDDPoznan
    Think about examples
    how your object should
    behave
    56
    

    View Slide

57. @eldudi #TDDPoznan
    Examples should cover
    only the interface of your
    object
    57
    

    View Slide

58. @eldudi #TDDPoznan
    Only the interface
    58
    

    View Slide

59. @eldudi #TDDPoznań
    Good habits
    59
    • Work outside-in
    • Use examples to clarify requirements
    • Use ubiquitous language
    

    View Slide

60. @eldudi #TDDPoznan
    Technical stuff now
    60
    

    View Slide

61. @eldudi #TDDPoznan
    Quick
    61
    

    View Slide

62. @eldudi #TDDPoznan
    Based on XCTest
    62
    

    View Slide

63. @eldudi #TDDPoznan
    Minimalistic
    implementation
    63
    

    View Slide

64. @eldudi #TDDPoznan
    Syntax
    64
    

    View Slide

65. @eldudi #TDDPoznan
    Configuring tests
    65
    

    View Slide

66. @eldudi #TDDPoznan
    Focusing tests
    66
    

    View Slide

67. @eldudi #TDDPoznań
    Focusing tests
    fdescribe("Example specs on NSString") {
    fit("lowercaseString returns a new string with
    everything in lower case") {
    fcontext("init with damping") {
    67
    

    View Slide

68. @eldudi #TDDPoznan
    PENDING
    68
    

    View Slide

69. @eldudi #TDDPoznań
    PENDING
    pending("lowercaseString returns a new string with
    everything in lower case") {}
    69
    

    View Slide

70. @eldudi #TDDPoznan
    x’ing tests
    70
    

    View Slide

71. @eldudi #TDDPoznań
    x’ing tests
    xdescribe("Example specs on NSString") {
    xit("lowercaseString returns a new string with
    everything in lower case") {
    xcontext("init with damping") {
    71
    

    View Slide

72. @eldudi #TDDPoznan
    Unit tests results
    72
    

    View Slide

73. @eldudi #TDDWarsaw
    Unit tests results
    How to understand the output?
    73
    

    View Slide

74. @eldudi #TDDWarsaw
    Xcode, AppCode,
    Command Line
    All give the same results. Devil is in the details
    74
    

    View Slide

75. @eldudi #TDDPoznań
    (…)
    -[SpecSuiteName passing_spec_name]
    Test Case '-[SpecSuiteName passing_spec_name]' started.
    Test Case '-[SpecSuiteName passing_spec_name]' passed
    (0.271 seconds).
    -[SpecSuiteName failling_spec_name]
    Test Case '-[SpecSuiteName failling_spec_name]' started.
    Test Case '-[SpecSuiteName failling_spec_name]' failed
    (0.002 seconds).
    (…)
    Executed 2 tests, with 1 failure (1 unexpected) in 0.273
    (0.278) seconds
    2 tests; 0 skipped; 1 failure; 1 exception; 0 pending
    75
    

    View Slide

76. @eldudi #TDDPoznań
    (…)
    -[SpecSuiteName passing_spec_name]
    Test Case '-[SpecSuiteName passing_spec_name]' started.
    Test Case '-[SpecSuiteName passing_spec_name]' passed
    (0.271 seconds).
    -[SpecSuiteName failling_spec_name]
    Test Case '-[SpecSuiteName failling_spec_name]' started.
    Test Case '-[SpecSuiteName failling_spec_name]' failed
    (0.002 seconds).
    (…)
    Executed 2 tests, with 1 failure (1 unexpected) in 0.273
    (0.278) seconds
    2 tests; 0 skipped; 1 failure; 1 exception; 0 pending
    76
    

    View Slide

77. @eldudi #TDDPoznań
    (…)
    -[SpecSuiteName passing_spec_name]
    Test Case '-[SpecSuiteName passing_spec_name]' started.
    Test Case '-[SpecSuiteName passing_spec_name]' passed
    (0.271 seconds).
    -[SpecSuiteName failling_spec_name]
    Test Case '-[SpecSuiteName failling_spec_name]' started.
    Test Case '-[SpecSuiteName failling_spec_name]' failed
    (0.002 seconds).
    (…)
    Executed 2 tests, with 1 failure (1 unexpected) in 0.273
    (0.278) seconds
    2 tests; 0 skipped; 1 failure; 1 exception; 0 pending
    77
    

    View Slide

78. @eldudi #TDDPoznań
    (…)
    -[SpecSuiteName passing_spec_name]
    Test Case '-[SpecSuiteName passing_spec_name]' started.
    Test Case '-[SpecSuiteName passing_spec_name]' passed
    (0.271 seconds).
    -[SpecSuiteName failling_spec_name]
    Test Case '-[SpecSuiteName failling_spec_name]' started.
    Test Case '-[SpecSuiteName failling_spec_name]' failed
    (0.002 seconds).
    (…)
    Executed 2 tests, with 1 failure (1 unexpected) in 0.273
    (0.278) seconds
    2 tests; 0 skipped; 1 failure; 1 exception; 0 pending
    78
    

    View Slide

79. @eldudi #TDDPoznań
    (…)
    -[SpecSuiteName passing_spec_name]
    Test Case '-[SpecSuiteName passing_spec_name]' started.
    Test Case '-[SpecSuiteName passing_spec_name]' passed
    (0.271 seconds).
    -[SpecSuiteName failling_spec_name]
    Test Case '-[SpecSuiteName failling_spec_name]' started.
    Test Case '-[SpecSuiteName failling_spec_name]' failed
    (0.002 seconds).
    (…)
    Executed 2 tests, with 1 failure (1 unexpected) in 0.273
    (0.278) seconds
    2 tests; 0 skipped; 1 failure; 1 exception; 0 pending
    79
    

    View Slide

80. @eldudi #TDDPoznan
    Run your tests from
    command line.
    80
    

    View Slide

81. @eldudi #TDDPoznan
    Seriously, do.
    It’s pretty awesome.
    81
    

    View Slide

82. @eldudi #TDDPoznan
    “Perfect” setup:
    Have your tests run each
    time you change something
    in a file.
    82
    

    View Slide

83. @eldudi #TDDPoznan
    Enhance your tests output.
    83
    

    View Slide

84. @eldudi #TDDPoznań
    (…)
    -[SpecSuiteName passing_spec_name]
    Test Case '-[SpecSuiteName passing_spec_name]' started.
    Test Case '-[SpecSuiteName passing_spec_name]' passed
    (0.271 seconds).
    -[SpecSuiteName failling_spec_name]
    Test Case '-[SpecSuiteName failling_spec_name]' started.
    Test Case '-[SpecSuiteName failling_spec_name]' failed
    (0.002 seconds).
    (…)
    Executed 2 tests, with 1 failure (1 unexpected) in 0.273
    (0.278) seconds
    2 tests; 0 skipped; 1 failure; 1 exception; 0 pending
    84
    

    View Slide

85. @eldudi #TDDPoznan
    85
    

    View Slide

86. @eldudi #TDDWarsaw
    Test Output
    xctool vs xcpretty
    86
    

    View Slide

87. @eldudi #TDDPoznań
    Resources & Contact
    @eldudi
    https://github.com/mobile-academy/swift-tdd-workshop-poznan
    pawel@dudek.mobi
    Code Examples
    Contact
    87
    

    View Slide