added a dependant destroy to the service_users

app/models/service.rb

@@ -6,7 +6,7 @@ class Service < ActiveRecord::Base
   include ActionView::Helpers::TextHelper
 
   belongs_to :user
-  has_many :service_users
+  has_many :service_users, :dependent => :destroy
 
   def public_message(post, length, url = "")
     url = "" if post.respond_to?(:photos) && post.photos.count == 0

spec/models/service_spec.rb

@@ -0,0 +1,22 @@
+require 'spec_helper'
+
+describe Service do
+
+  before do
+    @user = alice
+    @post = @user.post(:status_message, :text => "hello", :to =>@user.aspects.first.id)
+    @service = Services::Facebook.new(:access_token => "yeah")
+    @user.services << @service
+  end
+
+  it 'destroys the associated service_user' do
+    @service.service_users = [ServiceUser.create(:service_id => @service.id,
+                                                 :uid => "abc123",
+                                                 :photo_url => "a.jpg",
+                                                 :name => "a",
+                                                :person_id => bob.person.id)]
+    lambda{
+      @service.destroy
+    }.should change(ServiceUser, :count).by(-1)
+  end
+end