Test-Driven Development to avoid test painful

presented at CakeFest 2019

Transcript

1. © - BASE, Inc.
   Test-Driven Development
   to avoid test painful
   CakeFest
   . . - @hgsgtk
   

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2. © - BASE, Inc.
   Common story
   Programmer
   It works. I’m
   done!
   Production code (but No test code)
   Reviewer
   

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3. © - BASE, Inc.
   Common story
   Programmer
   Production code (but No test code)
   Reviewer
   Write a test,
   please.
   

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4. © - BASE, Inc.
   Common story
   Programmer
   It is a pain in the
   neck, but I got it.
   Production code (but No test code)
   Reviewer
   

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5. © - BASE, Inc.
   Test painful
   https://unsplash.com/photos/ajByNgzbklo
   

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6. © - BASE, Inc.
   Common story
   Programmer
   It works, but it’s
   difficult to write a test
   code.
   Production code (but Hard-to-Test Code)
   

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7. © - BASE, Inc.
   Common story
   Programmer
   Hmm
   Production code (but Hard-to-Test Code)
   

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8. © - BASE, Inc. https://unsplash.com/photos/VBe zj-JHBs
   Test painful
   

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9. https://unsplash.com/photos/jNrGkkvYk
   TDD solve these
   problems
   

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10. © - BASE, Inc.
    What this talk is about
    • Unit Test
    • Explain what is a test painful
    • Use Test-Driven Development to solve test
    painful
    

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11. © - BASE, Inc.
    What this talk is NOT about
    • End-to-End Test
    • PHPUnit basic how-to
    • Test executing environment (ex. CI)
    

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12. © - BASE, Inc.
    var_dump($hgsgtk);
    : @hgsgtk
    Kazuki Higashiguchi
    BASE BANK, Inc. / Dev Division / Tech Lead
    Software Developer
    CakePHP
    - use for business
    - contributor
    - cakephp/cakephp, cakephp/docs
    

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13. © - BASE, Inc.
    Agenda
    .Causes of test painful
    .Test-Driven Development
    .How to Use Test-Driven Development
    .Summary
    

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14. © - BASE, Inc.
    Agenda
    .Causes of test painful
    .Test-Driven Development
    .How to Use Test-Driven Development
    .Summary
    

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15. © - BASE, Inc.
    Cause
    Cause
    Cause
    Cause
    Cause
    Various causes of test painful
    Programmer
    Testing is terrible!
    Cause
    

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16. © - BASE, Inc.
    Various causes of test painful
    .No knowledge how to write unit tests
    .Too busy projects
    .No test code in production code
    .Too much bother to write tests
    .Hard-to-Test Code
    .Unmaintainable test codes
    

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17. . No knowledge how to write tests
    . Too busy projects
    . No test code in production code
    . Too much bother to write tests
    . Hard-to-Test Code
    . Unmaintainable test codes
    - Causes - - Possibly solutions -
    . Learn how to write tests
    . Improve project management
    . Legacy code improvement
    . Write the tests first
    . Testable code design
    . Tests with high readability and
    maintainability
    

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18. . No knowledge how to write tests
    . Too busy projects
    . No test code in production code
    . Too much bother to write tests
    . Hard-to-Test Code
    . Unmaintainable test codes
    - Causes - - Possibly solutions -
    . Learn how to write tests
    . Improve project management
    . Legacy code improvement
    . Write the tests first
    . Testable code design
    . Tests with high readability and
    maintainability
    FOCUS ON
    

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19. © - BASE, Inc.
    A case “Too much bother to write tests”
    Programmer
    It is a pain in the
    neck, but I got it.
    Production code (but No test code)
    Reviewer
    Write a test,
    please.
    

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20. © - BASE, Inc.
    Why does this happen?
    • In most cases, a programmer write test codes
    after writing production codes
    Programmer
    Write
    production codes
    Write
    test codes
    

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21. © - BASE, Inc.
    Why does this happen?
    • Writing tests may become “optional” process
    Programmer
    Write
    production codes
    Write
    test codes
    It works. I’m
    done!
    But I have to write
    test codes.
    

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22. © - BASE, Inc.
    Feel test painful
    https://unsplash.com/photos/eQTHhpTkBTY
    

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23. © - BASE, Inc.
    A case “Hard-to-Test Code”
    Programmer
    It works, but it’s
    difficult to write a test
    code.
    Hard-to-Test Code
    Hmm
    

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24. © - BASE, Inc.
    Hard-to-Test Code
    “Hard-to-Test Code is one factor that makes it
    difficult to write complete, correct automated
    tests in a cost-effective manner.”
    Meszarosf, Gerard. xUnit Test Patterns: Refactoring Test Code / Chapter . Code Smells
    

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25. © - BASE, Inc.
    Why does this happen?
    Programmer
    Programmer
    smooth-sailing
    production code
    (in the middle of coding it)
    complete
    everything
    Testable
    design
    In the middle of coding, a programmer doesn’t
    take care testable design
    

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26. © - BASE, Inc.
    Why does this happen?
    Programmer
    Programmer
    It works!
    production code
    (It’s done)
    complete
    everything
    Hard-to-
    Test Code
    No test code is often difficult to write tests
    But untestable
    

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27. © - BASE, Inc.
    Feel test painful
    https://unsplash.com/photos/_cbKur I A
    

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28. © - BASE, Inc.
    Summary “ . Causes of test painful”
    • There are various causes of test painful
    • Focus on two causes
    .Too much bother to write tests
    .Hard-to-Test Code
    

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29. © - BASE, Inc.
    Agenda
    .Causes of test painful
    .Test-Driven Development
    .How to Use Test-Driven Development
    .Summary
    

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30. https://unsplash.com/photos/jNrGkkvYk
    TDD
    

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31. © - BASE, Inc.
    Test-Driven Development (TDD)
    • The goal of TDD is “Clean code that works”
    • A way of managing fear during programming
    • Drive development by automated testing
    

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32. © - BASE, Inc.
    Don’t write a line of new code
    unless you first have a failing
    automated test
    Eliminate duplication
    TDD Rules
    https://www.eecs.yorku.ca/course_archive/ - /W/ /sectionM/case_studies/money/
    KentBeck_TDD_byexample.pdf
    

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33. © - BASE, Inc.
    TDD Cycle “Red-Green-Refactor”
    RED
    REFACTOR GREEN
    . Failed test
    . Passed
    . Refactor
    

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34. © - BASE, Inc.
    TDD Cycle
    .Add a little test
    .Run all tests, and fail
    .Make a little change
    .Run all tests and succeed
    .Refactor to remove duplication
    https://www.eecs.yorku.ca/course_archive/ - /W/ /sectionM/case_studies/money/
    KentBeck_TDD_byexample.pdf
    

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35. © - BASE, Inc.
    TDD steps
    .Make a to-do list to remind us what all we
    need to do
    .Work on the TDD cycle
    • “Temporary implementation” for changing
    from red to green quickly
    • Add to-do you notices along the way
    

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36. DEMONSTRATION
    https://unsplash.com/photos/xt tb oa o
    

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37. by CakePHP .
    

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38. © - BASE, Inc.
    To-do list
    Article details API
    • Article details API request returns success
    response
    • Article details API returns article resource
    

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39. © - BASE, Inc.
    . Add a little test
    RED
    REFAC
    TOR
    GREEN
    DEMO
    

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40. © - BASE, Inc.
    Possibly related to
    Cake\Controller\Exception\MissingActionE
    xception: "Action ArticlesController::view()
    could not be found, or is not accessible."
    . Run all tests, and fail DEMO
    

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41. © - BASE, Inc.
    . Make a little change
    RED
    REFAC
    TOR
    GREEN
    DEMO
    

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42. © - BASE, Inc.
    OK ( test, assertion)
    . Run all tests and succeed DEMO
    

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43. © - BASE, Inc.
    To-do list
    Article details API
    • Article details API request returns success
    response
    • Article details API returns article resource
    DEMO
    

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44. © - BASE, Inc.
    . Add a little test
    RED
    REFAC
    TOR
    GREEN
    DEMO
    

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45. © - BASE, Inc.
    Failed asserting that '[]'
    matches JSON string
    “{ }”.
    . Run all tests, and fail DEMO
    

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46. © - BASE, Inc.
    . Make a little change
    RED
    REFAC
    TOR
    GREEN
    DEMO
    

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47. © - BASE, Inc.
    OK ( test, assertion)
    . Run all tests and succeed DEMO
    

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48. © - BASE, Inc.
    . Refactor
    RED
    REFAC
    TOR
    GREEN
    DEMO
    

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49. © - BASE, Inc.
    . Refactor
    RED
    REFAC
    TOR
    GREEN
    DEMO
    

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50. © - BASE, Inc.
    To-do list
    Article details API
    • Article details API request returns success
    response
    • Article details API returns article resource
    DEMO
    

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51. © - BASE, Inc.
    Principles for TDD: “ -As” pattern
    • Use separate code paragraphs for each of the
    As.
    • -As
    • Arrange: variable declaration and initialization
    • Act: invoking the code under test
    • Assert: verify that expectations
    • This pattern makes it easy to revisit test code
    https://integralpath.blogs.com/thinkingoutloud/ / /principles_of_t.html
    

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52. © - BASE, Inc.
    Summary “ . Test-Driven Development”
    • The goal of TDD is “Clean code that works”
    • TDD cycle “Red-Green-Refactor”
    • Make a todo list and drive TDD cycle
    

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53. © - BASE, Inc.
    Agenda
    .Causes of test painful
    .Test-Driven Development
    .How to Use Test-Driven Development
    .Summary
    

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54. . No knowledge how to write tests
    . Too busy projects
    . No test code in production code
    . Too much bother to write tests
    . Hard-to-Test Code
    . Unmaintainable test codes
    - Causes - - Possibly solutions -
    . Learn how to write tests
    . Improve project management
    . Legacy code improvement
    . Write the tests first
    . Testable code design
    . Tests with high readability and
    maintainability
    FOCUS ON
    

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55. © - BASE, Inc.
    TDD solves two causes of test painful
    TDD
    • Test First
    • TDD Cycle
    Hard-to-Test Code
    Too much bother
    to write tests
    - Causes -
    

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56. © - BASE, Inc.
    TDD solves the cause “Too much bother to write tests”
    TDD
    • Test First
    • TDD Cycle
    Hard-to-Test Code
    Too much bother
    to write tests
    - Causes -
    Write the tests
    in TDD cycle
    

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57. © - BASE, Inc.
    Too much bother to write tests
    • In most cases, a programmer write test codes
    after writing production codes
    Programmer
    Write
    production codes
    Write
    test codes
    BEFORE
    

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58. © - BASE, Inc.
    Too much bother to write tests
    • Write test codes and production codes in TDD
    cycle
    • Write the tests first
    Programmer
    AFTER
    RED
    REFACT
    OR
    GREEN
    Write
    production codes
    Write
    test codes
    

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59. © - BASE, Inc.
    TDD solves the cause “Hard-to-Test Code”
    TDD
    • Test First
    • TDD Cycle
    Hard-to-Test Code
    Too much bother
    to write tests
    - Causes -
    Listening to the Tests
    

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60. © - BASE, Inc.
    Listening to the tests
    • TDD is about feedback on the code’s internal
    qualities
    • ex. coupling cohesion of classes, dependencies, effective information
    hiding
    Freeman, Steve. Growing Object-Oriented Software, Guided by Tests
    Chapter . Listening to the Tests
    

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61. © - BASE, Inc.
    Hard-to-Test Code
    Programmer
    Programmer
    It works!
    production code
    (It’s done)
    complete
    everything
    UnTestable
    design
    No test code is often difficult to write tests
    But untestable
    BEFORE
    

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62. © - BASE, Inc.
    Hard-to-Test Code
    Programmer
    Programmer
    production codes
    (with test codes)
    complete
    everything
    Testable
    design
    They becomes to be careful to make codes
    testable
    AFTER
    RED
    REFACT
    OR
    GREEN
    

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63. CASE STUDIES
    https://unsplash.com/photos/oBI NBP Lhg
    

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64. © - BASE, Inc.
    Can’t replace dependencies
    Bloated class/function
    Case studies
    

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65. © - BASE, Inc.
    Can’t replace dependencies
    Bloated class/function
    Case studies
    

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66. © - BASE, Inc.
    Example
    • A method to charge on order
    • Includes communication to external payment
    services
    

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67. © - BASE, Inc.
    Hard-to-Test Code BEFORE
    

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68. © - BASE, Inc.
    Hard-to-Test Code BEFORE
    It’s difficult to inject CardCharge class
    We can’t replace the dependency
    (without Magic)
    

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69. © - BASE, Inc.
    . Write a little test AFTER
    • Consider Dependency
    Injection to write a test
    • It is one of benefits to
    write a test first
    

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70. © - BASE, Inc.
    Can’t replace dependencies
    Bloated class/function
    Case studies
    

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71. © - BASE, Inc.
    Example
    • A controller action to handler order charge
    request
    • Save order resource
    • View order page
    

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72. © - BASE, Inc.
    Hard-to-Test Code BEFORE
    • A controller action
    

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73. © - BASE, Inc.
    Hard-to-Test Code BEFORE
    • Handle both requests
    

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74. © - BASE, Inc.
    Hard-to-Test Code BEFORE
    • The business logic in it
    

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75. © - BASE, Inc.
    Hard-to-Test Code BEFORE
    • Also there are another
    concerns
    

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76. © - BASE, Inc.
    Hard-to-Test Code BEFORE
    Mixed multiple use cases (request)
    Many procedures
    Hard-to-Test business logic code
    

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77. © - BASE, Inc.
    Make a to-do list
    • View the order page
    • Redirect when saving an order is succeeded
    • Calculate total amount of an order
    • Save order resource
    • Send charge request to external payment
    service
    • etc
    AFTER
    

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78. © - BASE, Inc.
    Run TDD cycle for each to-do
    • View the order page
    • Redirect when saving an order is succeeded
    • Calculate total amount of an order
    • Save order resource
    • Send charge request to external payment service
    • etc
    AFTER
    RED
    REFACT
    OR
    GREEN
    

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79. © - BASE, Inc.
    For instance
    • View the order page
    • Redirect when saving an order is succeeded
    • Calculate total amount of an order
    • Save order resource
    • Send charge request to external payment service
    • etc
    AFTER
    RED
    REFACT
    OR
    GREEN
    

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80. © - BASE, Inc.
    Calculate total amount of an order
    • This is a important logic, so many test patterns
    are needed
    • It may be better to write it in Entity
    AFTER
    

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81. © - BASE, Inc.
    . Write a little test AFTER
    

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82. © - BASE, Inc.
    Business logic in Model AFTER
    

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83. © - BASE, Inc.
    “Your designs must consist of many highly
    cohesive, loosely coupled components, just to
    make testing easy”
    https://www.eecs.yorku.ca/course_archive/ - /W/ /sectionM/case_studies/money/
    KentBeck_TDD_byexample.pdf
    A benefit of TDD
    

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84. © - BASE, Inc.
    Summary “ . How to Use Test-Driven Development”
    • TDD solves two causes of test painful
    .Too much bother to write tests
    .Hard-to-Test Code
    

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85. © - BASE, Inc.
    Agenda
    .Causes of test painful
    .Test-Driven Development
    .How to Use Test-Driven Development
    .Summary
    

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86. TDD solve test
    painful
    https://unsplash.com/photos/jvBXiynINGE
    

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87. Test is a design tool
    https://unsplash.com/photos/IClZBVw W A
    

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88. © - BASE, Inc.
    The solution to the problem of costly tests,
    however, is not to stop testing but instead to get
    better at it.
    Metz, Sandi. Practical Object-Oriented Design / Chapter Designing Cost-Effective Tests
    

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89. Any Questions?
    

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