Head First Fixture Replacement

ペパボ社内の RSpec 勉強会で Fixture Replacement について発表したスライドです。

Transcript

1. Head First Fixture Replacement @kyanny
2. Disclaimer: Samples Are Not Smartest, Not Enough, Not Exactly Correct
3. Test Environment then Fixture then Fixture Replacement
4. Test Environment
5. Test Suite Requires Isolate Environment
6. Unified Environment
7. User.create assert User.count == 1 # SUCCESS
8. User.create # Oops! Someone Create User # POST /users/create assert User.count == 1 # FAIL
9. Isolate Environment
10. mysql> show databases; +--------------------+ | Database | +--------------------+ | development | | test | | production | +--------------------+
11. User.create # For Development Environment # POST /users/create assert User.count == 1 # SUCCESS
12. Fixture
13. Fixture == Dummy Data for Tests
14. : ( user = User.create user.albums << Album.create user.albums << Album.create user.albums << Album.create assert user.albums.count >= 3
15. # fixtures/users.yml alice: id: 1 email: alice@example.com bob: id: 2 email: bob@example.com
16. # fixtures/albums.yml one: user_id: 1 two: user_id: 1 three: user_id: 1
17. : ) fixtures :users fixtures :albums user = users(:alice) assert user.albums.count >= 3
18. But... DRY
19. Fixture is Too Difficult To Maintain
20. Complex Association
21. # User has_many :bookmarks has_many :pages, :through => :bookmarks # Page has_many :bookmarks has_many :users, :through => :bookmarks # Bookmark belongs_to :user belongs_to: page
22. # fixtures/users.yml alice: id: 1 email: alice@example.com bob: id: 2 email: bob@example.com
23. # fixtures/pages.yml twitter: id: 1 url: http://twitter.com/ facebook: id: 2 url: http://facebook.com/
24. # fixtures/bookmarks.yml alice_twitter: user_id: 1 page_id: 1 bob_facebook: user_id: 2 page_id: 1 # Oops! Wrong id
25. bob = users(:bob) assert bob.pages.first.url == "http://facebook.com/" # FAIL
26. Complex Data
27. # fixtures/photos.yml one: album_id: 1 exif: | --- width: 1024 height: 768 f_number: 280/100
28. Fixture is Too Difficult To Maintain
29. Fixture Replacement
30. Fixture Replacement == Skeleton of Dummy Data for Tests
31. Fixture == Data itself Fixture Replacement == Skeleton of Data
32. # factories/users.rb Factory.define(:album) do |a| a.title "Album Title" a.password "Album Password" end album = Factory.create(:album) album = Factory.create(:album, :title => "Happy Wedding")
33. # factories/users.rb Factory.define(:alice) do |u| u.email "alice@example.com" end Factory.define(:bob) do |u| u.email "bob@example.com" end
34. # factories/users.rb Factory.sequence(:email) do |n| "user_#{n}@example.com" end Factory.define(:user) do |u| u.email { Factory.next(:email) } end
35. Flexible
36. # factories/pages.rb Factory.define(:twitter) do |p| p.url "http://twitter.com/" end Factory.define(:facebook) do |p| p.url "http://facebook.com/" end
37. # factories/users.rb Factory.define(:alice) do |u| u.pages {[ Factory(:twitter) ]} end Factory.define(:bob) do |u| u.pages {[ Factory(:facebook) ]} end
38. bob = Factory.create(:bob) assert bob.pages.first.url == "http://facebook.com/" # SUCCESS
39. But... Flexible
40. Fixture Replacement is Not a Silver Bullet
41. Children w/ Independent Parent
42. # factories/albums.rb Factory.define(:album) do |a| a.user { Factory(:user) } end Factory.define(:paid) do |a| a.user { Factory(:user) } end
43. 3.times do album = Factory.create(:album) end paid = Factory.create(:paid) user = paid.user assert user.albums.count == 4 # FAIL
44. user = Factory.create(:user) 3.times do Factory(:album, :user => user) end Factory(:paid, :user => user) assert user.albums.count == 4 # SUCCESS
45. Not DRY
46. Proposal: Fixture w/ Fixture Replacement
47. Test Context Arrangement Recipebook
48. First, Use Fixture. Complex, Then Use Fixture Replacement.
49. # fixtures/users.yml alice: id: 1 bob: id: 2
50. # fixtures/albums.yml one: user_id: 1 two: user_id: 1 three: user_id: 1 four: user_id: 1
51. fixtures :all user = users(:alice) assert user.albums.count == 4 # SUCCESS
52. # factories/photos.rb exif = { :width => 1024, :height => 768 } Factory.define(:photo) do |p| p.exif { exif.to_yaml } end
53. photo = Factory.create(:photo) assert photo.exif[:width] == 1024 # SUCCESS
54. Use The Right Tool In The Right Place
55. http://www.func09. com/wordpress/archives/532 http://eblog.drecom.jp/entry/14 http://www.slideshare.net/moro/test- context-arrangement-recipebook http://d.hatena.ne. jp/a666666/20110220/1298135559
56. end
57. Kensuke Nagae blog.kyanny.me @kyanny