Testing your FactoryGirl factories (and traits)

The standard way of testing your factories is with their own specs. Thoughtbot has some nice solution for this documented in their wiki. But how do you handle your factories' traits? Simple, you add them to your test code like this:

require 'spec_helper'

FactoryGirl.factories.map(&:name).each do |factory_name|
  describe "factory #{factory_name}" do
    it 'is valid' do
      factory = build(factory_name)

      if factory.respond_to?(:valid?)
        expect(factory).to be_valid, factory.errors.full_messages.join(',')
      end
    end
  end

  describe 'with trait' do
    FactoryGirl.factories[factory_name].definition.defined_traits.map(&:name).each do |trait_name|
      it "is valid with trait #{trait_name}" do
        factory = build(factory_name, trait_name)

        if factory.respond_to?(:valid?)
          expect(factory).to be_valid, factory.errors.full_messages.join(',')
        end
      end
    end
  end
end