belongs_to relationship creation should fail if foreign key does not exist.

ItemA belongs_to ItemB
item_b_id is not in table ItemAs.

ItemA.new.create_item_b -> does NOT raise error

A new ItemB is saved to db.

ItemA.first.item_b == nil

Env:
ree 1.8.7 2010.02
rails 3.0.0.rc, 3.0.0.rc2

This test identifies the issue. It can be placed in AR test/cases/associations/belongs_to_associations_test.rb

  class ItemA < ActiveRecord::Base
    belongs_to :item_b
  end
  class ItemB < ActiveRecord::Base
  end

  def test_creating_the_belonging_object_when_foreign_key_does_not_exist
    ActiveRecord::Base.connection.create_table :item_as, :force => true do |t|
      t.string :name
    end

    ActiveRecord::Base.connection.create_table :item_bs, :force => true do |t|
      t.string :name
    end
    
    item_a = ItemA.create!("name" => "Apple")
    item_b = item_a.create_item_b("name" => "(fan)Boy")
    assert_equal item_b, item_a.item_b
    item_a.save!
    item_a = ItemA.last
    assert_equal item_b, item_a.item_b
  end