added favorite unit tests

app/models/favorite.rb

@@ -1,2 +1,13 @@
-class Favorite < ActiveRecord::Base
+class Favorite
+  def self.table_name_for(user)
+    "favorites_#{user.id % 10}"
+  end
+  
+  def self.create(user, post)
+    ActiveRecord::Base.connection.execute("INSERT INTO #{table_name_for(user)} (user_id, post_id) VALUES (#{user.id}, #{post.id})")
+  end
+  
+  def self.destroy(user, post)
+    ActiveRecord::Base.connection.execute("DELETE FROM #{table_name_for(user)} WHERE user_id = #{user.id} AND post_id = #{post.id}")
+  end
 end

app/models/pool.rb

@@ -3,6 +3,7 @@ class Pool < ActiveRecord::Base
   validates_presence_of :name
   validates_format_of :name, :with => /\A[^\s;,]+\Z/, :on => :create, :message => "cannot have whitespace, commas, or semicolons"
   belongs_to :creator, :class_name => "User"
+  has_many :versions, :class_name => "PoolVersion"
   
   def self.create_anonymous(creator)
     pool = Pool.create(:name => "TEMP - #{Time.now.to_f}.#{rand(1_000_000)}", :creator => creator)

app/models/pool_version.rb

@@ -0,0 +1,6 @@
+class PoolVersion < ActiveRecord::Base
+  class Error < Exception ; end
+  
+  validates_presence_of :updater_id, :updater_ip_addr
+  belongs_to :pool
+end

app/models/post.rb

@@ -221,11 +221,13 @@ class Post < ActiveRecord::Base
     def add_favorite(user)
       self.fav_string += " fav:#{user.name}"
       self.fav_string.strip!
+      Favorite.create(user, self)
     end
     
     def remove_favorite(user)
       self.fav_string.gsub!(/fav:#{user.name}\b\s*/, " ")
       self.fav_string.strip!
+      Favorite.destroy(user, self)
     end
   end
   

app/models/post_version.rb

@@ -2,4 +2,5 @@ class PostVersion < ActiveRecord::Base
   class Error < Exception ; end
   
   validates_presence_of :updater_id, :updater_ip_addr
+  belongs_to :post
 end

app/models/user.rb

@@ -71,8 +71,30 @@ class User < ActiveRecord::Base
     end
   end
   
+  module FavoriteMethods
+    def favorite_posts(options = {})
+      favorites_table = Favorite.table_name_for(self)
+      before_id = options[:before]
+      before_id_sql_fragment = "AND favorites.id < #{before_id.to_i}" if before_id
+      limit = options[:limit] || 20
+      
+      sql = <<-EOS
+        SELECT posts.*, favorites.id AS favorite_id
+        FROM posts
+        JOIN #{favorites_table} AS favorites ON favorites.post_id = posts.id
+        WHERE
+          favorites.user_id = #{id}
+          #{before_id_sql_fragment}
+        ORDER BY favorite_id DESC
+        LIMIT #{limit.to_i}
+      EOS
+      Post.find_by_sql(sql)
+    end
+  end
+  
   include NameMethods
   include PasswordMethods
   extend AuthenticationMethods
+  include FavoriteMethods
 end
 

test/unit/favorite_test.rb

@@ -1,8 +1,40 @@
-require 'test_helper'
+require File.dirname(__FILE__) + '/../test_helper'
 
 class FavoriteTest < ActiveSupport::TestCase
-  # Replace this with your real tests.
-  test "the truth" do
-    assert true
+  context "A favorite" do
+    should "know which table it belongs to" do
+      user1 = Factory.create(:user)
+      user2 = Factory.create(:user)      
+      p1 = Factory.create(:post)
+      p2 = Factory.create(:post)
+    
+      p1.add_favorite(user1)
+      p2.add_favorite(user1)
+      p1.add_favorite(user2)
+    
+      favorites = user1.favorite_posts
+      assert_equal(2, favorites.size)
+      assert_equal(p2.id, favorites[0].id)
+      assert_equal(p1.id, favorites[1].id)
+      
+      favorites = user2.favorite_posts
+      assert_equal(1, favorites.size)
+      assert_equal(p1.id, favorites[0].id)
+    end
+    
+    should "filter before a given id" do
+      user1 = Factory.create(:user)
+      p1 = Factory.create(:post)
+      p2 = Factory.create(:post)
+      p3 = Factory.create(:post)
+      p1.add_favorite(user1)
+      p2.add_favorite(user1)
+      p3.add_favorite(user1)
+      favorites = user1.favorite_posts(:limit => 1)
+      favorites = user1.favorite_posts(:before => favorites.first.favorite_id)
+      assert_equal(2, favorites.size)
+      assert_equal(p2.id, favorites[0].id)
+      assert_equal(p1.id, favorites[1].id)
+    end
   end
 end