rails_record_id_bug.rb

# Activate the gem you are reporting the issue against.
gem 'activerecord', '4.1.0.beta1'
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 :records, force: true do |t|
    t.string :name
  end

  create_table :details, force: true do |t|
    t.integer :record_id
    t.string :name
  end
end

class Record < ActiveRecord::Base
  has_many :details
end

class Detail < ActiveRecord::Base
  belongs_to :record
end

class BugTest < Minitest::Test
  def test_association_stuff
    Record.delete_all
    Detail.delete_all

    record = Record.create!(name: "test")
    detail = record.details.build
    detail.name = "test"
    detail.save!

    assert_equal record.id, detail.record_id
    assert detail.persisted?, "Detail not persisted"
  end
end