Using a 'default' trait in FactoryGirl to avoid unnecessary association creation

When I do FactoryGirl.create :question_response, :open it will first create a default question and then create another inside the trait

It's not true. if you specify the trait with question, it will overwrite the factory behavior before creation so that it does not create a default question.

I checked it with FactoryGirl v4.5.0

Just in case someone else is looking for 'default trait' scenario, this was discussed with examples in https://github.com/thoughtbot/factory_bot/issues/528#issuecomment-18289143

Basically, you can define trait with defaults and then use it for different factories. And then you can use appropriate factory with needed configuration.

For example:

FactoryBot.define do
  trait :user_defaults do
    email { Faker::Internet.unique.email }
    username { Faker::Internet.unique.username }
    password { "test1234" }
  end

  factory :with_admin_role, class: User do
    user_defaults

    after(:create) do |user, _|
      user.add_role :admin
    end
  end

  factory :with_readonly_role, class: User do
    user_defaults

    after(:create) do |user, _|
      user.add_role :readonly
    end
  end
end