finished implication unit test

app/models/tag_implication.rb

@@ -1,23 +1,26 @@
 class TagImplication < ActiveRecord::Base
   attr_accessor :updater_id, :updater_ip_addr
+  before_save :clear_cache
   before_save :update_descendant_names
   after_save :update_descendant_names_for_parent
-  after_save :clear_cache
   after_destroy :clear_cache
   after_save :update_posts
   belongs_to :creator, :class_name => "User"
   belongs_to :updater, :class_name => "User"
   validates_presence_of :updater_id, :updater_ip_addr, :creator_id
+  validates_uniqueness_of :antecedent_name, :scope => :consequent_name
+  validate :absence_of_circular_relation
   
   def self.with_descendants(names)
-    names.map do |name|
-      ti = find_by_antecedent_name(name)
-      if ti
-        [name, ti.descendant_names_array]
-      else
-        name
-      end
-    end.flatten
+    ([names] + where(["antecedent_name IN (?)", Array(names)]).all.map {|x| x.descendant_names_array}).flatten
+  end
+  
+  def absence_of_circular_relation
+    # We don't want a -> b && b -> a chains
+    if self.class.exists?(["antecedent_name = ? and consequent_name = ?", consequent_name, antecedent_name])
+      self.errors[:base] << "Tag implication can not create a circular relation with another tag implication"
+      false
+    end
   end
   
   def parent
@@ -44,15 +47,21 @@ class TagImplication < ActiveRecord::Base
   
   def update_descendant_names
     self.descendant_names = descendants.join(" ")
+    self.class.logger.debug "#{antecedent_name}> updating descendants to #{descendant_names}"
   end
   
-  def update_descendant_names!
+  def update_descendant_names!(updater_id, updater_ip_addr)
     update_descendant_names
-    save
+    self.updater_id = updater_id
+    self.updater_ip_addr = updater_ip_addr
+    save!
   end
   
   def update_descendant_names_for_parent
-    parent.update_descendant_names! if parent
+    if parent
+      self.class.logger.debug "#{antecedent_name}> updating parent #{parent.antecedent_name}"
+      parent.update_descendant_names!(updater_id, updater_ip_addr)
+    end
   end
 
   def clear_cache
@@ -62,7 +71,7 @@ class TagImplication < ActiveRecord::Base
   def update_posts
     Post.find_by_tags(antecedent_name).find_each do |post|
       escaped_antecedent_name = Regexp.escape(antecedent_name)
-      fixed_tags = post.tag_string.sub(/\A#{escaped_antecedent_name} | #{escaped_antecedent_name} | #{escaped_antecedent_name}\Z/, " #{descendant_names} ").strip
+      fixed_tags = post.tag_string.sub(/\A#{escaped_antecedent_name} | #{escaped_antecedent_name} | #{escaped_antecedent_name}\Z/, " #{antecedent_name} #{descendant_names} ").strip
       post.update_attributes(
         :tag_string => fixed_tags,
         :updater_id => updater_id,