Test-Driven Development to avoid test painful

presented at CakeFest 2019

Transcript

1. © - BASE, Inc. Test-Driven Development to avoid test painful CakeFest . . - @hgsgtk
2. © - BASE, Inc. Common story Programmer It works. I’m done! Production code (but No test code) Reviewer
3. © - BASE, Inc. Common story Programmer Production code (but No test code) Reviewer Write a test, please.
4. © - BASE, Inc. Common story Programmer It is a pain in the neck, but I got it. Production code (but No test code) Reviewer
5. © - BASE, Inc. Test painful https://unsplash.com/photos/ajByNgzbklo
6. © - BASE, Inc. Common story Programmer It works, but it’s difficult to write a test code. Production code (but Hard-to-Test Code)
7. © - BASE, Inc. Common story Programmer Hmm Production code (but Hard-to-Test Code)
8. © - BASE, Inc. https://unsplash.com/photos/VBe zj-JHBs Test painful
9. https://unsplash.com/photos/jNrGkkvYk TDD solve these problems
10. © - BASE, Inc. What this talk is about • Unit Test • Explain what is a test painful • Use Test-Driven Development to solve test painful
11. © - BASE, Inc. What this talk is NOT about • End-to-End Test • PHPUnit basic how-to • Test executing environment (ex. CI)
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
13. © - BASE, Inc. Agenda .Causes of test painful .Test-Driven Development .How to Use Test-Driven Development .Summary
14. © - BASE, Inc. Agenda .Causes of test painful .Test-Driven Development .How to Use Test-Driven Development .Summary
15. © - BASE, Inc. Cause Cause Cause Cause Cause Various causes of test painful Programmer Testing is terrible! Cause
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
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
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
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.
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
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.
22. © - BASE, Inc. Feel test painful https://unsplash.com/photos/eQTHhpTkBTY
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
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
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
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
27. © - BASE, Inc. Feel test painful https://unsplash.com/photos/_cbKur I A
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
29. © - BASE, Inc. Agenda .Causes of test painful .Test-Driven Development .How to Use Test-Driven Development .Summary
30. https://unsplash.com/photos/jNrGkkvYk TDD
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
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
33. © - BASE, Inc. TDD Cycle “Red-Green-Refactor” RED REFACTOR GREEN . Failed test . Passed . Refactor
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
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
36. DEMONSTRATION https://unsplash.com/photos/xt tb oa o
37. by CakePHP .
38. © - BASE, Inc. To-do list Article details API • Article details API request returns success response • Article details API returns article resource
39. © - BASE, Inc. . Add a little test RED REFAC TOR GREEN DEMO
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
41. © - BASE, Inc. . Make a little change RED REFAC TOR GREEN DEMO
42. © - BASE, Inc. OK ( test, assertion) . Run all tests and succeed DEMO
43. © - BASE, Inc. To-do list Article details API • Article details API request returns success response • Article details API returns article resource DEMO
44. © - BASE, Inc. . Add a little test RED REFAC TOR GREEN DEMO
45. © - BASE, Inc. Failed asserting that '[]' matches JSON string “{ }”. . Run all tests, and fail DEMO
46. © - BASE, Inc. . Make a little change RED REFAC TOR GREEN DEMO
47. © - BASE, Inc. OK ( test, assertion) . Run all tests and succeed DEMO
48. © - BASE, Inc. . Refactor RED REFAC TOR GREEN DEMO
49. © - BASE, Inc. . Refactor RED REFAC TOR GREEN DEMO
50. © - BASE, Inc. To-do list Article details API • Article details API request returns success response • Article details API returns article resource DEMO
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
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
53. © - BASE, Inc. Agenda .Causes of test painful .Test-Driven Development .How to Use Test-Driven Development .Summary
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
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 -
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
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
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
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
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
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
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
63. CASE STUDIES https://unsplash.com/photos/oBI NBP Lhg
64. © - BASE, Inc. Can’t replace dependencies Bloated class/function Case studies
65. © - BASE, Inc. Can’t replace dependencies Bloated class/function Case studies
66. © - BASE, Inc. Example • A method to charge on order • Includes communication to external payment services
67. © - BASE, Inc. Hard-to-Test Code BEFORE
68. © - BASE, Inc. Hard-to-Test Code BEFORE It’s difficult to inject CardCharge class We can’t replace the dependency (without Magic)
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
70. © - BASE, Inc. Can’t replace dependencies Bloated class/function Case studies
71. © - BASE, Inc. Example • A controller action to handler order charge request • Save order resource • View order page
72. © - BASE, Inc. Hard-to-Test Code BEFORE • A controller action
73. © - BASE, Inc. Hard-to-Test Code BEFORE • Handle both requests
74. © - BASE, Inc. Hard-to-Test Code BEFORE • The business logic in it
75. © - BASE, Inc. Hard-to-Test Code BEFORE • Also there are another concerns
76. © - BASE, Inc. Hard-to-Test Code BEFORE Mixed multiple use cases (request) Many procedures Hard-to-Test business logic code
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
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
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
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
81. © - BASE, Inc. . Write a little test AFTER
82. © - BASE, Inc. Business logic in Model AFTER
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
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
85. © - BASE, Inc. Agenda .Causes of test painful .Test-Driven Development .How to Use Test-Driven Development .Summary
86. TDD solve test painful https://unsplash.com/photos/jvBXiynINGE
87. Test is a design tool https://unsplash.com/photos/IClZBVw W A
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
89. Any Questions?