如何在FactoryGirl工厂定义方法？

gem install factory_girl

FactoryGirl.define do
  factory :user do
    name "John Doe"
    email "john.doe@example.com"
    password "password"
  end
end

FactoryGirl.define do
  factory :user do
    name "John Doe"
    email "john.doe@example.com"
    password "password"

    factory :user_with_posts do
      after(:create) do |user|
        create_list(:post, 3, user: user)
      end
    end
  end
end

user_with_posts = create(:user_with_posts)