licence.rb

class Licence < ActiveRecord::Base
  belongs_to :parent_licence, :class_name => 'Licence'
  has_many :nested_licences, :class_name => 'Licence', :foreign_key => 'parent_licence_id', :dependent => :destroy
  accepts_nested_attributes_for :nested_licences
  validates_associated :nested_licences

  def clone
    cloned = super
    cloned.nested_licences = nested_licences.map { |nested_licence| nested_licence.clone }
    cloned
  end
end

licences.yml

# So I have this fixture, but when running any tests which use it, Licence.find(1).nested_licences is always empty.

licence_1:
  id: 1
  organisation_id: 1
  user_id: 1
  owner_organisation_id: 2
  owner: 'TwoCorp'
  dongle_id: 2
  profile_id: 5   # server
  expiry: '2009-11-01'
  success: true
  notes: 'Server licence'
  created_at: '2009-01-01 00:00:00'
licence_1_1:
  id: 4
  organisation_id: 1
  user_id: 1
  parent_licence_id: 1
  count: 3
  profile_id: 1   # legal desktop
  expiry: '2009-11-01'
  load_worker_count: 8