thoughtbot--factory_bot/spec/acceptance/modify_inherited_spec.rb

describe "modifying inherited factories with traits" do
  before do
    define_model("User", gender: :string, admin: :boolean, age: :integer)
    FactoryBot.define do
      factory :user do
        trait(:female) { gender { "Female" } }
        trait(:male)   { gender { "Male" } }

        trait(:young_admin) do
          admin { true }
          age   { 17 }
        end

        female
        young_admin

        factory :female_user do
          gender { "Female" }
          age { 25 }
        end

        factory :male_user do
          gender { "Male" }
        end
      end
    end
  end

  it "returns the correct value for overridden attributes from traits" do
    expect(FactoryBot.build(:male_user).gender).to eq "Male"
  end

  it "returns the correct value for overridden attributes from traits defining multiple attributes" do
    expect(FactoryBot.build(:female_user).gender).to eq "Female"
    expect(FactoryBot.build(:female_user).age).to eq 25
    expect(FactoryBot.build(:female_user).admin).to eq true
  end

  it "allows modification of attributes created via traits" do
    FactoryBot.modify do
      factory :male_user do
        age { 20 }
      end
    end

    expect(FactoryBot.build(:male_user).gender).to eq "Male"
    expect(FactoryBot.build(:male_user).age).to eq 20
    expect(FactoryBot.build(:male_user).admin).to eq true
  end
end