Test case for issue 1629

test.rb

unless File.exists?('Gemfile')
  File.write('Gemfile', <<-GEMFILE)
    source 'https://rubygems.org'
    gem 'rails', github: 'rails/rails'
    gem 'sqlite3'
  GEMFILE

  system 'bundle'
end

require 'bundler'
Bundler.setup(:default)

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

# 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 do |t|
  end

  create_table :addresses do |t|
    t.integer :addressable_id
    t.string :addressable_type
  end

  class User < ActiveRecord::Base
    has_one :address, :as => :addressable
    accepts_nested_attributes_for :address
  end

  class Address < ActiveRecord::Base
    belongs_to :addressable, :polymorphic => true
    validates_associated :addressable
  end

  class BugTest < MiniTest::Unit::TestCase
    def test_polymorphic_nested_attributes
      u = User.new({:address => Address.new}) 
      assert u.save
    end
  end
end

This test passes because we have validates_associated, if we had validates_presence_of it would fail.