1. Below And
Beneath TDD
Test-Last Development and other
real world test patterns
Noel Rappin
@noelrap
Pathfinder Development
pathf.com
railsprescriptions.com

2. http://www.railsrx.com

3. TEST REFACTOR
FAIL PASS
CODE Rx

4. TEST REFACTOR
Why does testing work?
FAIL PASS
Why does testing fail?
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5. TEST REFACTOR
What does it mean for
testing to “work”?
FAIL PASS
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6. TEST REFACTOR
Improve effectiveness
of team and
quality of code
NOT
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A perfect guarantee of
code correctness
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7. TEST REFACTOR
for me, tdd is about
confidence &
accountability &
responsibility & design &
reusability & portability &
flexibility & testing &
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trustworthiness &
teamwork & initiative &
flow & that's all i can
think of at the moment.
CODE
-- Kent Beck
Rx

8. TEST REFACTOR
Accurate view of code
Small, incremental steps
FAIL PASS
Scaffold for change
Focus for development
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9. TEST REFACTOR
What does it mean for
testing to “fail”?
FAIL PASS
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10. TEST REFACTOR
Decrease efficiency and
code quality
FAIL PASS
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11. TEST REFACTOR
“It feels like there's a
hidden door that everyone
who tests has found and
walked through...
There are a bunch of us...
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that would love to join
the party, but don't know
where to find
the door.”
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12. TEST REFACTOR
If you are stuck in a
window or banging your
head against the wall,
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this will help
you get to the door
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13. TEST REFACTOR
FAIL PASS
CODE Rx

14. TEST REFACTOR
Test-Driven
Development
FAIL PASS
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15. TEST REFACTOR
AKA: Behavior-Driven
Development
or
FAIL PASS
Test-First
Programming
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16. TEST REFACTOR
TDD Code has:
small pieces
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high cohesion
loose coupling
minimal side-effects
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17. TEST REFACTOR
☺Accurate view of code
☺Small, incremental steps
FAIL PASS
☺Scaffold for change
☺Focus for development
CODE Rx

18. TEST REFACTOR
FAIL PASS
CODE Rx

19. TEST
Lose the refactoring
FAIL PASS
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20. TEST
Development, that
FAIL PASS
happens
to have tests
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21. TEST
Symptoms:
FAIL PASS
Increased duplicaton in
code.
Long methods
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22. TEST
Benefits:
FAIL PASS
May seem faster at first
CODE Rx

23. TEST
Over time...
FAIL PASS
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24. TEST
☺Accurate view of code
Small, incremental steps
FAIL PASS
Scaffold for change
☺Focus for development
CODE Rx

25. TEST
Fix by:
FAIL PASS
Cleaning up your mess
CODE Rx

26. TEST REFACTOR
FAIL PASS
CODE Rx

27. TEST REFACTOR
FAIL PASS
TEST
FAIL
CODE Rx

28. TEST REFACTOR
assert_equal(nil, actual) assert_equal(4.314, actual)
FAIL PASS
TEST
actual = 4.314
FAIL
CODE Rx

29. TEST REFACTOR
Data-Driven Testing
or
FAIL PASS
Using your program
as a calculator
TEST
FAIL
CODE Rx

30. TEST REFACTOR
Benefits:
Failed Test Guaranteed
FAIL PASS
Value may be hard to
calculate TEST
FAIL
CODE Rx

31. TEST REFACTOR
Pitfalls:
Can mask ignorance
of domain
FAIL PASS
Can lead to worse
TEST
problems
FAIL
CODE Rx

32. TEST REFACTOR
Accurate view of code
☺Small, incremental steps
FAIL PASS
☺Scaffold for change
☺Focus for development TEST
FAIL
CODE Rx

33. TEST REFACTOR
assert_equal(nil, actual) assert_equal(4.314, actual)
FAIL PASS
TEST
actual = 4.314
FAIL
CODE Rx

34. REFACTOR
CODE
actual = 4.314
assert_equal(4.314, actual)
PASS
TEST
Rx

35. CODE REFACTOR
Test-Next Development
aka
PASS
Code-Driven
Development
TEST
Rx

36. CODE REFACTOR
Symptoms:
No more failing tests
Tweaking tests to
PASS
match code
Coverage drop
TEST
Rx

37. CODE REFACTOR
Benefits:
Useful when exploring
PASS
Useful when testing
views
TEST
Rx

38. CODE REFACTOR
Pitfalls:
Easily slides into worse
patterns
PASS
Hard to avoid
coverage gaps
TEST
Rx

39. CODE REFACTOR
Accurate view of code
☺Small, incremental steps
PASS
Scaffold for change
Focus for development
TEST
Rx

40. CODE REFACTOR
Tautology Based
Development
PASS
TEST
Rx

41. CODE REFACTOR
Definition:
Tests that can’t
PASS
fail
TEST
Rx

42. CODE REFACTOR
Symptoms:
Bugs that should have
been covered
PASS
Mock object
misuse
TEST
Rx

43. CODE REFACTOR
☹Accurate view of code
☺Small, incremental steps
PASS
Scaffold for change
☹Focus for development
TEST
Rx

44. CODE REFACTOR
Mitigation:
Try to separate
code assertions
PASS
from application
data
TEST
Rx

45. CODE REFACTOR
PASS
TEST
Rx

46. CODE REFACTOR
CODE
CODE
CODE
PASS
CODE
CODE
CODE
TEST
Rx

47. CODE REFACTOR
CODE
CODE
CODE Test-Last Development PASS
CODE
CODE
CODE
TEST
Rx

48. CODE REFACTOR
CODE
Symptoms:
CODE
Significant coverage drop
CODE
PASS
Uncovered bugs
CODE
Harder to write tests
CODE
CODE
TEST
Rx

49. CODE REFACTOR
CODE
CODE This is one way in which
we talk past each other
CODE
PASS
Unit tests ≠ TDD
CODE
CODE
CODE
TEST
Rx

50. CODE REFACTOR
CODE Pitfall:
CODE Tests get more
CODE expensive
PASS
CODE Lower quality tests
CODE Programmer boredom
CODE
TEST
Rx

51. CODE REFACTOR
CODE
CODE Needed when:
CODE Hitting corner case PASS
CODE Dealing with legacy
CODE
CODE
TEST
Rx

52. CODE REFACTOR
CODE ☹Accurate view of code
CODE ☹Small, incremental steps
CODE
PASS
Scaffold for change
CODE
☹Focus for development
CODE
CODE
TEST
Rx

53. CODE REFACTOR
Escape by:
CODE
CODE Start the TDD process
CODE Don’t look back PASS
CODE Catch up to legacy
parts as you touch
CODE
them
CODE
TEST
Rx

54. CODE REFACTOR
CODE
CODE
CODE
PASS
CODE
CODE
CODE
TEST
Rx

55. CODE REFACTOR
CODE
CODE
CODE
Run
CODE
CODE
CODE
TEST
Rx

56. CODE REFACTOR
CODE
CODE
Coverage Driven
CODE Development Run
CODE
CODE
CODE
TEST
Rx

57. CODE REFACTOR
CODE
CODE
Symptom:
CODE
Run
Tests without assertions
CODE
CODE
CODE
TEST
Rx

58. CODE REFACTOR
CODE
Why?
CODE
Minimal approach to
CODE
Run
legacy
CODE
Hard to reach code
CODE
CODE
TEST
Rx

59. CODE REFACTOR
CODE ☹Accurate view of code
CODE ☹Small, incremental steps
CODE
Run
☹Scaffold for change
CODE
☹Focus for development
CODE
CODE
TEST
Rx

60. TEST REFACTOR
FAIL PASS
CODE Rx

61. TEST REFACTOR
TEST TEST
TEST TEST
FAIL PASS
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62. TEST REFACTOR
TEST TEST
TEST TEST
Lots of Test
FAIL PASS
First Development
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63. TEST REFACTOR
TEST TEST
TEST TEST
Symptom:
FAIL PASS
Lots of test failures at
once during initial
developmment
CODE Rx

64. TEST REFACTOR
TEST TEST
TEST TEST
Benefit:
FAIL PASS
Allows planning for future
code
CODE Rx

65. TEST REFACTOR
TEST TEST
TEST TEST Cost:
Loss of focus
FAIL PASS
Somewhat harder to
write code against
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66. TEST REFACTOR
TEST TEST
TEST TEST
Middle Ground:
FAIL PASS
RSpec pending
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67. TEST REFACTOR
TEST TEST
☺Accurate view of code
TEST TEST
Small, incremental steps
FAIL PASS
☺Scaffold for change
Focus for development
CODE Rx

68. TEST REFACTOR
FAIL PASS
CODE Rx

69. SETUP REFACTOR
TEST
PASS
FAIL
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70. SETUP REFACTOR
TEST
Setup Driven Development PASS
FAIL
CODE Rx

71. SETUP REFACTOR
Symptom:
TEST
Large, brittle setup
methods
PASS
Slow tests
FAIL
High-level tests
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72. SETUP REFACTOR
TEST
Costs:
PASS
This is why people
hate testing
FAIL
CODE Rx

73. SETUP REFACTOR
Accurate view of code
TEST
☹Small, incremental steps
PASS
☺Scaffold for change
Focus for development
FAIL
CODE Rx

74. SETUP REFACTOR
TEST
Escape by:
Mock Objects PASS
Real unit tests
FAIL
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75. TEST REFACTOR
FAIL PASS
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76. TEST REFACTOR
Another problem:
End to end failures
FAIL PASS
Lack of focus
Expectation failures
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77. Cucumber REFACTOR
TEST
A potential solution PASS
FAIL
CODE Rx

78. Cucumber REFACTOR
TEST Acceptance Test-Driven
PASS
Development
FAIL
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79. Cucumber REFACTOR
Symptom:
TEST
PASS
You are writing
acceptance tests
FAIL
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80. Cucumber REFACTOR
Costs:
TEST
PASS
Additional layer of test
code, indirection
FAIL
CODE Rx

81. Cucumber REFACTOR
Benefits:
TEST
PASS
Increased focus,
improved feedback
FAIL
CODE Rx

82. Cucumber REFACTOR
☺Accurate view of code
☺Small, incremental steps
TEST
PASS
☺Scaffold for change
☺Focus for development
FAIL
CODE Rx

83. TEST REFACTOR
FAIL PASS
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84. TEST REFACTOR
And So:
FAIL PASS
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85. TEST REFACTOR
Constant feedback
and
FAIL PASS
baby steps
CODE Rx

86. TEST REFACTOR
Focus on what
comes next
Failure Driven
FAIL PASS
Development
CODE Rx

87. TEST REFACTOR
Good code has
small pieces
high cohesion
FAIL PASS
loose coupling
minimal side-effects
CODE Rx

88. TEST REFACTOR
Invisible cost of bugs
or
FAIL PASS
Done vs. “Done Done”
CODE Rx

89. TEST REFACTOR
Go write
some tests!
FAIL PASS
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90. TEST REFACTOR
Rails Test Prescriptions
http://www.railsrx.com
Pathfinder Development
FAIL PASS
http://www.pathf.com
http://www.pathf.com/blogs
@noelrap @railsrx
BoF: 9PM CODE
Wed Pavillion 9-10 Rx