gistfile1.rb

require "rubygems"
require "dm-core"
require "dm-validations"
require "spec"

DataMapper.setup(:default, "sqlite3::memory:")

module MarkForDestruction
  def mark_for_destruction
    @marked_for_destruction = true
  end
  def marked_for_destruction?
    @marked_for_destruction
  end
end

module Save
  def save(*args)
    if marked_for_destruction?
      destroy
    else
      super
    end
  end
end

class Person
  include DataMapper::Resource
  include MarkForDestruction
  include Save
  property :id, Serial
  has 1, :profile
end

class Profile
  include DataMapper::Resource
  include MarkForDestruction
  include Save
  property :id, Serial
  property :person_id, Integer, :nullable => false
  belongs_to :person
end

describe "Resource#save" do
  before(:each) do
    DataMapper.auto_migrate!
  end
  it "should save a newly associated resource" do
    p = Person.new
    p.profile = Profile.new
    p.save
    Person.all.size.should  == 1  
    Profile.all.size.should == 1  
  end
  it "should destroy a resource that is marked_for_destruction (FAILS)" do
    person  = Person.create
    profile = Profile.create :person => person
    person.profile.mark_for_destruction
    
    # FAILS 
    # because this is empty, dm never tries to call my
    # overwritten save, and thus never destroys the resource
    person.send(:child_associations).should_not be_empty
    
    person.save
    Person.all.size.should  == 1
    Profile.all.size.should == 0
  end
end