Factory GirlA Brief Introduction Using Ruby on Rails

Factory GirlA Brief Introduction Using Ruby on Rails

Yet Another Blog Example

What’s Factory Girl?

A Replacement for Fixtures

Provides a Simple DSL

Keeps TestsFocused & Readable

Builds Objects Instead of Database Records

Installation

Gemfile

group :development, :test do gem ‘factory_girl_rails’end

Gemfile

$ bundle install

Defining a Factory

spec/factories/

spec/factories/users.rb

spec/factories/posts.rb

spec/factories/comments.rb

spec/factories/products.rb

spec/factories/users.rb

FactoryGirl.define do factory :user do name ‘Joe Blow’ email ‘joe.blow@example.com’ password ‘p@ssw0rd’ admin false endend

spec/factories/users.rb

spec/models/user_spec.rb

spec/models/user_spec.rb

describe User do

end

spec/models/user_spec.rb

describe User do subject { FactoryGirl.create(:user) }

end

spec/models/user_spec.rb

describe User do subject { FactoryGirl.create(:user) }

its(:name) { should == ‘Joe Blow’ }

end

spec/models/user_spec.rb

describe User do subject { FactoryGirl.create(:user) }

its(:name) { should == ‘Joe Blow’ } its(:email) { should == ‘joe.blow@example.com’ }

end

describe User do subject { FactoryGirl.create(:user) }

its(:name) { should == ‘Joe Blow’ } its(:email) { should == ‘joe.blow@example.com’ }

it { should_not be_admin }end

spec/models/user_spec.rb

FactoryGirl.create(:user)

FactoryGirl.build(:user)

FactoryGirl.build_stubbed(:user)

spec/spec_helper.rb

RSpec.configure do |config| config.include FactoryGirl::Syntax::Methodsend

spec/spec_helper.rb

FactoryGirl.create(:user)

create(:user)

build(:user)

build_stubbed(:user)

spec/models/user_spec.rb

describe User do subject { create(:user) }

its(:name) { should == ‘Joe Blow’ } its(:email) { should == ‘joe.blow@example.com’ }

it { should_not be_admin }end

Overriding Attributes

Keep Only Relevant Attributes in Tests

spec/models/user_spec.rb

context ‘a duplicate email address’ do it { should_not be_valid }end

context ‘a duplicate email address’ do let(:first_user) { User.create(name: ‘Joe First’, email: ‘joe@example.com’, password: ‘test123’, admin: false) } subject { User.new(name: ‘Joe Duplicate’, email: first_user.email, password: ‘test123’, admin: false) }

it { should_not be_valid }end

spec/models/user_spec.rb

context ‘a duplicate email address’ do let(:user) { create(:user) } subject { build(:user, email: user.email) }

it { should_not be_valid }end

spec/models/user_spec.rb

Lazy Attributes

Lazy Attributes Are Dynamic Attributes

spec/factories/posts.rb

FactoryGirl.define do factory :post do title ‘This is my post.’ content ‘There are many like it, but this one is mine.’ published_at Time.now endend

irb(main):001:0> FactoryGirl.create(:post)

irb(main):001:0> FactoryGirl.create(:post)=> #<Post id: 1, title: “This is my post.”, content: “There are many like it, but this one is mine.”, published_at: 2012-12-20 23:47:34 UTC>

group :development, :test do gem ‘factory_girl_rails’ gem ‘ffaker’end

Gemfile

spec/factories/posts.rb

FactoryGirl.define do factory :post do title { Faker::Lorem.sentence } content { Faker::Lorem.sentences.join(‘ ’) } published_at { Time.now } endend

irb(main):001:0> FactoryGirl.create(:post)

irb(main):001:0> FactoryGirl.create(:post)=> #<Post id: 2, title: “Lorem ipsum dolor sit amet, consectetur adipiscing elit.”, content: “Pellentesque adipiscing varius suscipit …”, published_at: 2012-12-20 23:48:14 UTC>

irb(main):001:0> FactoryGirl.create(:post)=> #<Post id: 3, title: “Nulla id augue ut mauris pharetra tincidunt ac sed velit.”, content: “Nullam tincidunt, dolor quis pellentesque …”, published_at: 2012-12-20 23:49:06 UTC>

Sequences

Reuse Common Attributes

FactoryGirl.define do sequence :email do |n| “person#{n}@example.com” endend

spec/factories/sequences.rb

FactoryGirl.define do factory :user do name { Faker::Name.name } email password ‘p@ssw0rd’ admin false endend

spec/factories/users.rb

person1@example.com

person1@example.com,person2@example.com

person1@example.com,person2@example.com,person3@example.com

person1@example.com,person2@example.com,person3@example.com,etc.

Dependent Attributes

Attributes FromOther Attributes

spec/factories/users.rb

FactoryGirl.define do factory :user do name ‘Joe Blow’ email ‘joe.blow@example.com’ password ‘p@ssw0rd’ admin false endend

spec/factories/users.rb

FactoryGirl.define do factory :user do name ‘Joe Blow’ email { ‘#{name.gsub(/\s/, ‘.’)}@example.com’.downcase } password ‘p@ssw0rd’ admin false endend

irb(main):001:0> FactoryGirl.create(:user)=> #<User id: 1, name: “Joe Blow”, email: “joe.blow@example.com”, password: “p@ssw0rd”, admin: false>

irb(main):001:0> FactoryGirl.create(:user, name: ‘Joe Mama’)=> #<User id: 2, name: “Joe Mama”, email: “joe.mama@example.com”, password: “p@ssw0rd”, admin: false>

Traits

Specify Types Of Factories

describe Post do context ‘an unpublished post’ do subject { create(:post, published_at: nil) }

it ‘will never be read’ do # ... end endend

FactoryGirl.define do factory :post do title { Faker::Lorem.sentence } content { Faker::Lorem.sentences.join(‘ ’) } published_at { Time.now } endend

spec/factories/posts.rb

FactoryGirl.define do factory :post do title { Faker::Lorem.sentence } content { Faker::Lorem.sentences.join(‘ ’) } published_at { Time.now } trait :unpublished do published_at nil end endend

spec/factories/posts.rb

describe Post do context ‘an unpublished post’ do subject { create(:post, :unpublished) }

it ‘will never be read’ do # ... end endend

spec/models/post_spec.rb

Associations

Build Associated Objects From Factories

class Post < ActiveRecord::Base belongs_to :userend

app/models/post.rb

irb(main):001:0> FactoryGirl.create(:post)=> #<Post id: …, title: “…”, content: “…”, published_at: …, user: nil>

FactoryGirl.define do factory :post do title { Faker::Lorem.sentence } content { Faker::Lorem.sentences.join(‘ ’) } published_at { Time.now } trait :unpublished do published_at nil end endend

spec/factories/posts.rb

FactoryGirl.define do factory :post do user title { Faker::Lorem.sentence } content { Faker::Lorem.sentences.join(‘ ’) } published_at { Time.now } trait :unpublished do published_at nil end endend

spec/factories/posts.rb

irb(main):001:0> FactoryGirl.create(:post)=> #<Post …, user: #<User id: 123, name: “John Wayne”, …>>

Transient Attributes

Customize Behavior With Fake Attributes

FactoryGirl.define do factory :post do ignore do unapproved false end

title { unapproved ? “ಠ_ಠ” : “This is my post.” } endend

spec/factories/posts.rb

FactoryGirl.define do factory :post do ignore do unapproved false end

title { unapproved ? “ಠ_ಠ” : “This is my post.” } endend

spec/factories/posts.rb

FactoryGirl.define do factory :post do ignore do unapproved false end

title { unapproved ? “ಠ_ಠ” : “This is my post.” } endend

spec/factories/posts.rb

irb(main):001:0> FactoryGirl.create(:post)=> #<Post id: 2, title: “This is my post.”>

irb(main):001:0> FactoryGirl.create(:post, unapproved: true)=> #<Post id: 2, title: “ಠ_ಠ”>

Creating or Building Multiple Objects

Build a Shitload Of Objects

FactoryGirl.create_list(:model, 5)

FactoryGirl.build_list(:model, 5)

FactoryGirl.build_stubbed_list(:model, 5)

irb(main):001:0> FactoryGirl.create_list(:post, 5)

irb(main):001:0> FactoryGirl.create_list(:post, 5)=> [#<Post id: 1, title: “This is my post.”>, #<Post id: 2, title: “This is my post.”>, #<Post id: 3, title: “This is my post.”>, #<Post id: 4, title: “This is my post.”>, #<Post id: 5, title: “This is my post.”>]

Callbacks

Execute Arbitrary Code When Building & Creating

class User < ActiveRecord::Base has_many :postsend

app/models/user.rb

FactoryGirl.define do factory :user_with_posts do ignore do posts_count 5 end

after(:create) do |user, evaluator| FactoryGirl.create_list(:post, evaluator.posts_count, user: user) end endend

spec/factories/users.rb

irb(main):001:0> FactoryGirl.create(:user).posts.length=> 0

irb(main):001:0> FactoryGirl.create(:user_with_posts).posts.length=> 5

irb(main):001:0> FactoryGirl.create(:user_with_posts,posts_count: 15).posts.length=> 15

Wrapping Up...

Factory Girl is Magic

Easier to Maintain

Less of a Headache

Fun to Work With

Questions?