How to create has_and_belongs_to_many associations in Factory girl

Question

Given the following

class User < ActiveRecord::Base
  has_and_belongs_to_many :companies
end

class Company < ActiveRecord::Base
  has_and_belongs_to_m         


        

Answer 1

Update for Rails 5:

Instead of using has_and_belongs_to_many association, you should consider: has_many :through association.

The user factory for this association looks like this:

FactoryBot.define do
  factory :user do
    # user attributes

    factory :user_with_companies do
      transient do
        companies_count 10 # default number
      end

      after(:create) do |user, evaluator|
         create_list(:companies, evaluator.companies_count, user: user)
      end
    end
  end
end

You can create the company factory in a similar way.

Once both factories are set, you can create user_with_companies factory with companies_count option. Here you can specify how many companies the user belongs to: create(:user_with_companies, companies_count: 15)

You can find detailed explanation about factory girl associations here.