Factory Girl

How to use Factory Girl for creating model fakes in your test. Video where I talk over it the whole time: https://vimeo.com/119875543

Transcript

1. Factory Girl 1
2. Summing up a complex human being in two hours is like an MTV spot about Nelson Mandela cut to a Kanye West track. 1 Brian Holcomb, CinemaBlend.com 2
3. factory_girl thoughtbot/factory_girl 3
4. Usage 4
5. Integrate it $ mkdir -p ./spec/support $ vim ./spec/support/factory_girl.rb # spec/support/factory_girl.rb RSpec.configure do |config| config.include FactoryGirl::Syntax::Methods end 5
6. Define them $ mkdir -p ./spec/factories $ vim ./spec/factories/user_factories.rb # spec/factories/user_factories.rb FactoryGirl.define do factory :user do first_name "Jon" last_name "Snow" is_nights_watch true end end 6
7. Refine them FactoryGirl.define do factory :user do first_name "Jon" last_name "Snow" is_nights_watch true trait(:knows_nothing) do knows [] end end end 7
8. Relate them FactoryGirl.define do factory :animal do species "Sciurus carolinensis" name "squirrel" end factory :direwolf, class: Animal do species "Canis dirus" name "direwolf" end end 8
9. Relate them FactoryGirl.define do factory :user do first_name "Jon" last_name "Snow" is_nights_watch true trait(:knows_nothing) { knows [] } trait(:has_animal) { animal } trait(:has_direwolf) do association :animal, factory: :direwolf end end end 9
10. Make them saved_instance = FactoryGirl.create(:user) # <User id: 1, first_name: "Jon", last_name: "Snow"> non_persisted = FactoryGirl.build(:user) # <User id: nil, first_name: "Jon", last_name: "Snow"> hash = FactoryGirl.attributes_for(:user) # { first_name: "Jon", last_name: "Snow" } If you're using Rspec and have included the FactoryGirl helpers… saved_instance = create(:user) # <User id: 1, first_name: "Jon", last_name: "Snow"> 10
11. Make them user = create(:user, :knows_nothing, :has_direwolf) # <User id: 1, first_name: "Jon", last_name: "Snow", knows: []> user.animal # <Animal id: 1, species: "Canis dirus", name: "direwolf"> 11
12. Make them master_at_arms = create(:user, :has_animal, first_name: "Alliser", last_name: "Thorne") # <User id: 1, first_name: "Alliser", last_name: "Thorne"> master_at_arms.animal # <Animal id: 1, species: "Sciurus carolinensis", name: "squirrel"> 12
13. Pro-tips Show off your awesome skills 13
14. Association aliases factory :user do # Instead of `association :animal, factory: :direwolf` direwolf end 14
15. Child factories with traits factory :user do on_nights_watch false # Traits can be cascaded/layered. Last one gets precedence. trait(:nights_watch) { on_nights_watch(true) } trait(:has_direwolf) { direwolf } factory :jon_snow, traits: %i(nights_watch has_direwolf) end # To use... create(:jon_snow) # <User id: 1, name: "Jon Snow", on_nights_watch: true> 15
16. Lazily-computed attributes factory :user do # Use when your data is not static. signed_up_at { 21.seconds.ago } end 16
17. Sequences factory :user do # To ensure your data is unique-ish. sequence(:codename) { |idx| "user-#{idx}" } end 17
18. Fake things with Faker factory :user do first_name { Faker::Name.first_name } email { Faker::Internet.email } bitcoin { Faker::Bitcoin.address } about { Faker::Lorem.paragraph(2).join("\n") } end Make your tests less dependent on specific data. This is a Good Thing™. 18
19. Dependent attributes factory :user do first_name "Jon" last_name "Snow" # This is super simple, but must be lazily-evaluated ygritte_says { "You know nothing, #{first_name} #{last_name}."} end 19
20. Non-persisted (transient) attributes factory :user do ignored do broke_vows false end name "Jon Snow" after_create do |user, factory_instance| if factory_instance.broke_vows user.revoke_nights_watch_status! end end end 20
21. Callbacks factory :user do after_build { |user| user.update_column(:last_name, "Snow") } after_create { |user| user.give_direwolf! } end 21
22. Batch creation animals = FactoryGirl.create_list(:animal, 25) unsaved_direwolves = FactoryGirl.build_list(:direwolf, 5) lannisters = FactoryGirl.create_list(:user, last_name: "Lannister", sigil: "Lion") 22
23. http://github.com/ thoughtbot/factory_girl gem install factory_girl 23