have a deleted_user_fallback mixin and cost_entry, labor_budget_item and rate using it

* deleted_user_fallback will return the deleted user upon asking for user when the user_id of the including model points to a user who no longer exists

app/models/cost_entry.rb

@@ -4,6 +4,7 @@ class CostEntry < ActiveRecord::Base
   belongs_to :project
   belongs_to :issue
   belongs_to :user
+  include Costs::DeletedUserFallback
   belongs_to :cost_type
   belongs_to :cost_object
   belongs_to :rate, :class_name => "CostRate"

app/models/labor_budget_item.rb

@@ -1,6 +1,7 @@
 class LaborBudgetItem < ActiveRecord::Base
   belongs_to :cost_object
   belongs_to :user
+  include Costs::DeletedUserFallback
 
   validates_length_of :comments, :maximum => 255, :allow_nil => true
   validates_presence_of :user

app/models/rate.rb

@@ -3,6 +3,7 @@ class Rate < ActiveRecord::Base
   validate :validate_date_is_a_date
 
   belongs_to :user
+  include Costs::DeletedUserFallback
   belongs_to :project
 
   attr_accessible :rate, :project, :valid_from

lib/costs/deleted_user_fallback.rb

@@ -0,0 +1,23 @@
+module Costs
+  module DeletedUserFallback
+    def self.included(base)
+      base.send(:include, InstanceMethods)
+
+      base.class_eval do
+        alias_method_chain :user, :deleted_user_fallback
+      end
+    end
+
+    module InstanceMethods
+      def user_with_deleted_user_fallback(force_reload = true)
+        associated_user = user_without_deleted_user_fallback(force_reload)
+
+        if associated_user.nil? && read_attribute(:user_id).present?
+          associated_user = DeletedUser.first
+        end
+
+        associated_user
+      end
+    end
+  end
+end

spec/models/cost_entry_spec.rb

@@ -217,7 +217,18 @@ describe CostEntry do
           before { cost_type.deleted_at = Date.new }
 
           it { cost_entry.should_not be_valid }
+    describe :user do
+      describe "WHEN a non existing user is provided (i.e. the user has been deleted)" do
+        before do
+          cost_entry.save!
+          user.destroy
         end
+
+        it { cost_entry.reload.user.should == DeletedUser.first }
+      end
+
+      describe "WHEN an existing user is provided" do
+        it { cost_entry.user.should == user }
       end
     end
   end

spec/models/default_hourly_rate_spec.rb

@@ -0,0 +1,30 @@
+require File.dirname(__FILE__) + '/../spec_helper'
+
+describe DefaultHourlyRate do
+  let(:project) { Factory.create(:project) }
+  let(:user) { Factory.create(:user) }
+  let(:rate) { Factory.build(:default_hourly_rate, :project => project,
+                                                   :user => user) }
+
+  describe :user do
+    describe "WHEN an existing user is provided" do
+      before do
+        rate.user = user
+        rate.save!
+      end
+
+      it { rate.user.should == user }
+    end
+
+    describe "WHEN a non existing user is provided (i.e. the user is deleted)" do
+      before do
+        rate.user = user
+        rate.save!
+        user.destroy
+        rate.reload
+      end
+
+      it { rate.user.should == DeletedUser.first }
+    end
+  end
+end

spec/models/hourly_rate_spec.rb

@@ -0,0 +1,30 @@
+require File.dirname(__FILE__) + '/../spec_helper'
+
+describe HourlyRate do
+  let(:project) { Factory.create(:project) }
+  let(:user) { Factory.create(:user) }
+  let(:rate) { Factory.build(:hourly_rate, :project => project,
+                                           :user => user) }
+
+  describe :user do
+    describe "WHEN an existing user is provided" do
+      before do
+        rate.user = user
+        rate.save!
+      end
+
+      it { rate.user.should == user }
+    end
+
+    describe "WHEN a non existing user is provided (i.e. the user is deleted)" do
+      before do
+        rate.user = user
+        rate.save!
+        user.destroy
+        rate.reload
+      end
+
+      it { rate.user.should == DeletedUser.first }
+    end
+  end
+end

spec/models/labor_budget_item_spec.rb

@@ -57,6 +57,32 @@ describe LaborBudgetItem do
     end
   end
 
+  describe :user do
+    describe "WHEN an existing user is provided" do
+      before do
+        item.save!
+        item.reload
+        item.update_attribute(:user_id, user.id)
+        item.reload
+      end
+
+      it { item.user.should == user }
+    end
+
+    describe "WHEN a non existing user is provided (i.e. the user has been deleted)" do
+      before do
+        item.save!
+        item.reload
+        item.update_attribute(:user_id, user.id)
+        user.destroy
+        item.reload
+      end
+
+      it { item.user.should == DeletedUser.first }
+      it { item.user_id.should == user.id }
+    end
+  end
+
   describe :valid? do
     describe "WHEN hours, cost_object and user are provided" do
       it "should be valid" do