An introduction to Behaviour-Driven Development, the second-generation agile methodology that aims at delivering software that matters. Most of us know that BDD has something to do with tests and the way code is produced. But what is it exactly? How does it differ from Test-Driven Development? We'll discover the technical principles and practices lying at the heart of BDD, as experienced from a naive programmer perspective. But BDD is not only about writing better tests and code. It really holds higher purposes...

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The first steps of a Behaviour-Driven Developer

2. Julien Biezemans
@jbpros

3. Who?

4. You happen to write code...

5. useless,

6. delivered (too) late,

7. fragile,

8. difficult to deploy,

9. impenetrable,

10. hard to maintain.

11. BDD

12. Dan North
@tastapod

13. “BDD is a second-generation, outside-
in, pull-based, multiple-stakeholder,
multiple-scale, high-automation,
agile methodology.”

14. “It describes a cycle of interactions
with well-defined outputs, resulting in
the delivery of working, tested
software that matters.”

15. Test-Driven
Development

16. Red, Green, Refactor

17. Where to start?

18. What to test?

19. Behaviour

21. From Test to
Behaviour

22. Most important missing
behaviour today?

23. Business value

24. Story

25. As ...
I want ...
So that ...

26. Estimation

27. Acceptance criteria

28. Scenario

29. Context ➔ Event ➔ Outcome

30. Given ➔ When ➔ Then

31. Ubiquitous Language

32. BDD in Ruby/Rails

33. Stories + Scenarios
=
Cucumber features

34. Cucumber
http://github.com/cucumber

35. Full-stack, deliverable

36. Outside-in

37. Acceptance tests
Unit tests
Code

40. Run feature

42. Missing step definition
#fail

43. Write step definition

44. features/step_definitions/tamagotchi_steps.rb

45. bin/app.rb

46. Run feature

48. Missing code
#fail

49. RSpec
http://github.com/rspec

50. Write spec

51. spec/lib/tamagotchi_spec.rb

52. Run spec

54. Missing code
#fail

55. Make it pass

56. lib/tamagotchi.rb

58. Refactor

59. Repeat until the
feature passes

61. Design

62. spec/lib/tamagotchi_spec.rb

63. spec/lib/tamagotchi_spec.rb

65. lib/tamagotchi.rb

67. lib/tamagotchi.rb

69. spec/lib/tamagotchi_spec.rb

71. Stubs

72. spec/lib/tamagotchi_spec.rb

74. lib/tamagotchi.rb

76. spec/lib/tamagotchi_spec.rb

77. spec/lib/tamagotchi_spec.rb

80. Spec everything your
step definitions need

81. spec/lib/tamagotchi_spec.rb

82. lib/tamagotchi.rb

85. spec/lib/tamagotchi_spec.rb

86. lib/tamagotchi.rb

89. features/step_definitions/tamagotchi_steps.rb

94. Living documentation

95. Ruby on Rails

96. View ➔ Controller ➔ Model

97. From Programmer
to Developer

98. program v.
To provide (a machine) with
a set of coded working
instructions.

99. develop v.
To bring out the capabilities
of; bring to a more advanced
or effective state.

100. Deliberate discovery

101. Know what
you don’t know

102. Know what
you don’t know
you don’t know

103. Learn the domains

104. Learn the tools

105. Know the people

106. Feedback

107. Real options

108. Practice

109. Your code is now...

110. useful,

111. delivered on time,

112. robust,

113. easily deployable,

114. intelligible,

115. maintainable,

116. A piece of software
that matters.

117. Don’t deliver features

118. Ship
capabilities!