Duplicate associations in Factory Girl - ruby-on-rails

Question

I am using fixtures to load test data on a Ruby on Rails project. I moved to Factory Girl, but I am getting duplicate entries for associations.
I have a Group model and a Value model. A Group can have multiple Values.
Also, I am using Cucumber for my tests. And FactoryGirl.lint to populate the database.
My fixtures
groups.yml
group_1:
name: "Flavour"
values.yml
value_1:
name: "Strawberry"
group: group_1
value_2:
name: "Mint"
group: group_1
value_3:
name: "Chocolate"
group: group_1
This works just fine. A single Group is created and the 3 Values are attached to it.
My factories
groups.rb
FactoryGirl.define do
factory :group do
name "Flavour"
end
end
values.rb
FactoryGirl.define do
factory :value_1, class: :value do
name "Strawberry"
group
end
factory :value_2, class: :value do
name "Mint"
group
end
factory :value_3, class: :value do
name "Chocolate"
group
end
end
This is not working. Factory Girl is creating 3 Groups, each one associated to 1 Value.
Is this normal behaviour for Factory Girl?
Also, I read that use_transactional_fixtures should be set to true. This is already the case.

Answer 1

I don't think you really have grasped the conceptual differences between using fixtures and factories.
With fixtures you have these static object definitions that get chucked into the database on each test run. Its like your database has a "zero" state with a bunch of data already. Feels nice, warm and fuzzy (Oh I don't have to set everything up, so nice!) but its a horrible idea in reality since it masks any errors caused by an empty table!
With factories you define objects dynamically instead and create them when needed. You use a tool like database_cleaner to clean out any residual state between tests. You start each test with nothing.
FactoryGirl.lint does not populate the database. Its a linter that checks that your factory definitions are correct.
There is absolutely zero point in using factory_girl if you just create a bunch of fixtures with it. So instead you want to do something like:
FactoryGirl.define do
factory :value do
name { ["Strawberry", "Mint", "Chocolate"].sample }
group
end
end
One of the mental hurdles of going from fixtures to factories is you have to stop writing tests like if you where using fixture data:
describe "GET /users/:id" do
let!(:user){ FactoryGirl.create(:user) }
let(:json) { JSON.parse(response.body) }
before { get users_path(#user), format: :json }
it "has the correct name" do
# bad
expect(json["name"]).to eq "John Doe" # strong coupling to factory!
# good
expect(json["name"]).to eq user.name # we don't know what the factory generates.
end
end
If you have to have a test where a certain factory value must be known or if a factory needs to be associated to a certain object then do it explicitly instead of making a mess of your definitions.
let(:user) { FactoryGirl.create(:user, name: 'Max') }
let(:item) { user.items.create(FactoryGirl.attributes_for(:item)) }
it "has an awesome name" do
expect(user.name).to eq 'Max'
end
it "is associated" do
expect(item.user).to eq user
end

Answer 2

Your value factories are told to use the group factory for their group, and the group factory is told to make a new group with name 'Flavor'. What you want to do differently is that you want the group factory to return the existing 'Flavor' rather than a new one. Here is how to do that.
FactoryGirl.define do
factory :group, class: :group do
name 'Flavor'
initialize_with {Group.find_or_initialize_by(name: name)}
end
end
That is saying if you already have a group with desired name, use existing group. Written as above so that there is a default name, and you get the same 'use existing if present' behavior when passing in an alternate name.