Factory Girl: How to set up a has_many/through association

Try something like this. You want to build a detail object and append it to the job’s detail association. When you use after_create, the created job will be yielded to the block. So you can use FactoryGirl to create a detail object, and add it to that job’s details directly.

factory :job do
  ...

  after_create do |job|
    job.details << FactoryGirl.create(:detail)
  end
end