Behaviour Driven Development

An introduction into Agile, User stories, Cynefin framework BDD, PHPSpec and Behat

Transcript

1. Behaviour Driven Development James Cowie
2. Who am I • James Cowie • Software Engineer • Session Digital • BDD Practitioner • @jcowie • github.com/jamescowie
3. Software development problems
4. Traditional Software Development • Slow feedback cycles • Expensive to change • Upfront documentation
5. Waterfall Requirements Analysis Design Code Test
6. Agile 2001 • Start the conversation • Iterations • Process of engagement
7. TDD / Agile Cycle Requirements Acceptance Design Code Test around 20 minutes
8. Introducing BDD “Software development practice that emphasises development through an example-based conversations with users and stakeholders of the system.“
9. Introducing BDD “Software development practice that emphasises development through an example-based conversations with users and stakeholders of the system.“
10. Evolution / Process of BDD • Inspired by eXtreme programming and Agile • Example workshops • User stories • Story mapping
11. What is BDD • Evolved from Test-first development • Common language • Behaviour • Discovering and delivery what matters most first
12. BDD Cycle Narrative Why? Examples Implement Refactor Describe How
13. Cynefin
14. disorder Exploring Cynefin Simple Complex Chaotic Complicated
15. Simple Best Practice
16. Complicated Good Practice
17. Complex Emergent
18. Chaos novel
19. Disorder
20. How do this help ? Unknowns
21. User Stories
22. Imperative Style
23. As a Zoologist I want to add a new animal to the site So that I can share my animal knowledge with the community Scenario: successful submission Given I'm on the animal creation page When I fill in Name with 'Alligator' And select Phylum as 'Chordata' And fill in Animal Class with 'Sauropsida' And check Lay Eggs And click the Create button Then I should see the notice 'Thank you for your animal submission!' And the page should include the animal's name, phylum, animal class, order, family, and
24. Declarative Style
25. As a Zoologist I want to add a new animal to the site So that I can share my animal knowledge with the community Scenario: successful submission Given I'm on the animal creation page When I add a new animal Then I should see the page for my newly created animal And the notice 'Thank you for your animal submission!'
26. Given When Then
27. Given I am trying to do something When I make an action on it Then I expect something in return
28. Given I am trying to do something Context
29. When I make an action on it Event
30. Then I expect something in return outcome
31. What are the parts to a Story ?
32. Title Narrative Role: Feature Benefit Scenarios
33. What makes a good story ?
34. Clear connection to the business goal
35. Clear deliverable value to beneficiary
36. Easily understood by all parties
37. Always benefits a party
38. BDD Tools
39. Implementation === PHPSpec Conversation === Behat
40. PHPSpec
41. Behat
42. Installing the tools
43. curl -sS https://getcomposer.org/installer | php
44. { "require-dev": { "phpspec/phpspec": "2.*", "behat/behat": "3.*" }, "autoload": { “psr-0": {"": "src/"} }, "config": { "bin-dir": "bin" } }
45. Feature: I can calculate string values As a user I want to be able to calculate the sum of two strings. Scenario: Returns 0 when no string values are passed Given the current value to calculate is " " When I calculate the sum Then the sum value for " " is zero
46. class FeatureContext implements Context, SnippetAcceptingContext { protected $value; /** * @Given the current value to calculate is :value */ public function theCurrentValueToCalculateIs($value) { $this->value = $value; }
47. /** * @When I calculate the sum */ public function iCalculateTheSum() { $output = (new Acme\Calculator())->calculate($this->value); } /** * @Then the sum value for :arg1 is zero */ public function theSumValueForIsZero($arg1) { expect($this->output)->toBe(0); }
48. Doh. No Calculator class
49. phpspec describe Acme\Calculator
50. function it_should_be_zero_when_empty_string_is_passed() { $this->calculate(" ")->shouldReturn(0); }
51. PHPSPEC RUN
52. Scenario: Returns 0 when no string values are passed Given the current value to calculate is " " When I calculate the sum Then the sum value for " " is zero --- Failed scenarios: features/feature-file.feature:5
53. Time to write some code !
54. <?php namespace Acme; class Calculator { public function calculate($number) { return 0; } }
55. Scenario: Returns 0 when no string values are passed Given the current value to calculate is " " When I calculate the sum Then the sum value for " " is zero
56. Scenario: Returns the number if only a single number is passed Given the current value to calculate is "1" When I calculate the sum Then the sum value for "1" is one
57. Fail Then the sum value for "1" is one Expected <value>"1"</value>, but got <value>[integer:0]</value>
58. Spec
59. function it_should_return_the_number_for_single_number() { $this->calculate("1")->shouldReturn(1); }
60. public function calculate($number) { if ($number == " " ) { return 0; } else { return (int)$number; } }
61. Back to green
62. phpspec r --format=pretty Acme\Calculator 10 ✔ is initializable 15 ✔ should return zero when empty string is passed 20 ✔ should return the number for single number Feature: I can calculate string values As a user I want to be able to calculate the sum of two strings. Scenario: Returns 0 when no string values are passed Given the current value to calculate is " “ When I calculate the sum Then the sum value for " " is zero Scenario: Returns the number if only a single number is passed Given the current value to calculate is “1" When I calculate the sum Then the sum value for "1" is one
63. Modelling By Example
64. Any Questions ?