require 'rubygems'
require 'active_record'

ActiveRecord::Base.establish_connection({
  :adapter => 'mysql',
  :database => 'spike',
  :username => 'root',
  :password => '',
  :encoding => 'utf8'
})

ActiveRecord::Schema.define do
  create_table :children, :force => true do |t|
    t.column :parent_id, :integer
  end
  create_table :parents, :force => true do |t|
    t.column :name,  :integer
  end
  execute %{alter table children add constraint
            fk_children_parents foreign key (parent_id)
            references parents(id)}
end

class Child < ActiveRecord::Base
  belongs_to :parent
end
class Parent < ActiveRecord::Base
end

class FKChecksTest < Test::Unit::TestCase

  def setup
    @parent = Parent.create
    @child = Child.create(:parent_id => @parent.id)
  end

  def with_fk_checks_off
    ActiveRecord::Base.connection.update('SET FOREIGN_KEY_CHECKS = 0')
    yield
    ActiveRecord::Base.connection.update('SET FOREIGN_KEY_CHECKS = 1')
  end

  def test_expect_deleting_target_of_foreign_key_raises
    assert_raises(ActiveRecord::StatementInvalid) {@parent.destroy}
    assert !@parent.frozen?
    assert !@child.reload.parent.nil?
  end

  def test_deleting_with_fk_checks_off
    with_fk_checks_off { @parent.destroy }
    assert @parent.frozen?
    assert @child.reload.parent.nil?
  end

  def test_with_fk_checks_off_cleans_up
    parent2 = Parent.create
    child2 = Child.create(:parent_id => parent2.id)
    with_fk_checks_off { @parent.destroy }
    assert_raises(ActiveRecord::StatementInvalid) {parent2.destroy}
  end
end