gistfile1.builder

require "active_record"

module HasManyPreventDestroy
  def has_many(association, options = {}, &extension)
    before_destroy { send(association).empty? } if options.delete(:prevent_destroy)
    super(association, options, &extension)
  end
end

class Foo < ActiveRecord::Base
  extend HasManyPreventDestroy

  has_many :bars, :prevent_destroy => true
end

class Bar < ActiveRecord::Base
  belongs_to :foo
end

ActiveRecord::Base.establish_connection(:adapter => "sqlite3", :database => ":memory:")

ActiveRecord::Schema.define(:version => 0) do
  create_table :foos, :force => true do |t|
    t.string :name
  end
  
  create_table :bars, :force => true do |t|
    t.string :name
    t.integer :foo_id
  end
end

require "test/unit"

class DeletesTest < Test::Unit::TestCase
  def test_deletes
    foo = Foo.create!
    foo.bars.create!

    foo.destroy

    assert_not_nil Foo.find(foo.id)
  end
end