FactoryGirl and polymorphic associations

Question

The design

I have a User model that belongs to a profile through a polymorphic association. The reason I chose this design can be found here. To summarize, there a

Answer 1

It seems that polymorphic associations in factories behave the same as regular Rails associations.

So there is another less verbose way if you don't care about attributes of model on "belongs_to" association side (User in this example):

# Factories
FactoryGirl.define do
  sequence(:email) { Faker::Internet.email }

  factory :user do
    # you can predefine some user attributes with sequence
    email { generate :email }
  end

  factory :artist do
    # define association according to documentation
    user 
  end
end

# Using in specs    
describe Artist do      
  it 'created from factory' do
    # its more naturally to starts from "main" Artist model
    artist = FactoryGirl.create :artist        
    artist.user.should be_an(User)
  end
end

FactoryGirl associations: https://github.com/thoughtbot/factory_girl/blob/master/GETTING_STARTED.md#associations

Answer 2

You can also solve this using nested factories (inheritance), this way you create a basic factory for each class then nest factories that inherit from this basic parent.

FactoryGirl.define do
    factory :user do
        # attributes_for user
        factory :artist_profile do
            association :profile, factory: :artist
        end
        factory :musician_profile do
            association :profile, factory: :musician
        end
    end
end

You now have access to the nested factories as follows:

artist_profile = create(:artist_profile)
musician_profile = create(:musician_profile)

Hope this helps someone.

Answer 3

I currently use this implementation for dealing with polymorphic associations in FactoryGirl:

In /spec/factories/users.rb:

FactoryGirl.define do

  factory :user do
    # attributes for user
  end

  # define your Artist factory elsewhere
  factory :artist_user, parent: :user do
    profile { create(:artist) }
    profile_type 'Artist'
    # optionally add attributes specific to Artists
  end

  # define your Musician factory elsewhere
  factory :musician_user, parent: :user do
    profile { create(:musician) }
    profile_type 'Musician'
    # optionally add attributes specific to Musicians
  end

end

Then, create the records as usual: FactoryGirl.create(:artist_user)

Answer 4

Use traits like this;

FactoryGirl.define do
    factory :user do
        # attributes_for user
        trait :artist do
            association :profile, factory: :artist
        end
        trait :musician do
            association :profile, factory: :musician
        end
    end
end

now you can get user instance by FactoryGirl.create(:user, :artist)

Answer 5

Although there is an accepted answer, here is some code using the new syntax which worked for me and might be useful to someone else.

spec/factories.rb

FactoryGirl.define do

  factory :musical_user, class: "User" do
    association :profile, factory: :musician
    #attributes for user
  end

  factory :artist_user, class: "User" do
    association :profile, factory: :artist
    #attributes for user
  end

  factory :artist do
    #attributes for artist
  end

  factory :musician do
    #attributes for musician
  end
end

spec/models/artist_spec.rb

before(:each) do
  @artist = FactoryGirl.create(:artist_user)
end

Which will create the artist instance as well as the user instance. So you can call:

@artist.profile

to get the Artist instance.

Answer 6

Factory_Girl callbacks would make life much easier. How about something like this?

Factory.define :user do |user|
  #attributes for user
end

Factory.define :artist do |artist|
  #attributes for artist
  artist.after_create {|a| Factory(:user, :profile => a)}
end

Factory.define :musician do |musician|
  #attributes for musician
  musician.after_create {|m| Factory(:user, :profile => m)}
end