Example script showing a bug when trying to set singular_collection_ids with a primary key set on relationship

singular_collection_ids_test.rb

begin
  require 'bundler/inline'
rescue LoadError => e
  $stderr.puts 'Bundler 1.10 or later is required. Please update Bundler'
  raise e
end

gemfile(true) do
  source 'https://rubygems.org'
  # Activate the gem you are reporting the issue against.
  gem 'activerecord', '4.2.7.1'
  gem 'sqlite3'
  gem 'pry'
end

require 'active_record'
require 'minitest/autorun'
require 'logger'

# Ensure backward compatibility with Minitest 4
Minitest::Test = MiniTest::Unit::TestCase unless defined?(Minitest::Test)

# This connection will do for database-independent bug reports.
ActiveRecord::Base.establish_connection(
  adapter: 'sqlite3', database: ':memory:'
)
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :users, force: true do |t|
  end

  create_table :user_businesses, force: true do |t|
    t.belongs_to :user
    t.string :business_id, index: true
  end

  create_table :businesses, force: true do |t|
    t.string :uuid
  end
end

class User < ActiveRecord::Base
  has_many :user_businesses
  has_many :businesses, through: :user_businesses
end

class UserBusiness < ActiveRecord::Base
  belongs_to :user
  belongs_to :business, primary_key: :uuid
end

class Business < ActiveRecord::Base
end

class SingularCollectionAssociationIdsTest < Minitest::Test
  def test_singular_collection_ids=
    user = User.create!
    business = Business.create!(uuid: SecureRandom.uuid)

    exception = assert_raises ActiveRecord::RecordNotFound do
      user.business_ids = [business.uuid]
    end

    assert_equal(
      "Couldn't find Business with 'id'=#{business.uuid.to_i}",
      exception.message
    )
  end
end