use GeneratedFeatureMethods module for associations

activerecord/lib/active_record/associations/builder/association.rb

@@ -6,7 +6,7 @@ class Association #:nodoc:
     # Set by subclasses
     class_attribute :macro
 
-    attr_reader :model, :name, :options, :reflection, :mixin
+    attr_reader :model, :name, :options, :reflection
 
     def self.build(model, name, options)
       new(model, name, options).build
@@ -14,8 +14,10 @@ def self.build(model, name, options)
 
     def initialize(model, name, options)
       @model, @name, @options = model, name, options
-      @mixin = Module.new
-      @model.__send__(:include, @mixin)
+    end
+
+    def mixin
+      @model.generated_feature_methods
     end
 
     def build

activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb

@@ -15,10 +15,14 @@ def build
 
       def define_destroy_hook
         name = self.name
-        mixin.send(:define_method, :destroy_associations) do
-          association(name).delete_all
-          super()
-        end
+        model.send(:include, Module.new {
+          class_eval <<-RUBY, __FILE__, __LINE__ + 1
+            def destroy_associations
+              association(#{name.to_sym.inspect}).delete_all
+              super
+            end
+          RUBY
+        })
       end
 
       # TODO: These checks should probably be moved into the Reflection, and we should not be

activerecord/lib/active_record/attribute_methods.rb

@@ -8,12 +8,6 @@ module AttributeMethods #:nodoc:
     include ActiveModel::AttributeMethods
 
     module ClassMethods
-      def inherited(child_class)
-        # force creation + include before accessor method modules
-        child_class.generated_attribute_methods
-        super
-      end
-
       # Generates all the attribute related methods for columns in the database
       # accessors, mutators and query methods.
       def define_attribute_methods

activerecord/lib/active_record/base.rb

@@ -450,6 +450,20 @@ class << self # Class methods
                :having, :create_with, :uniq, :to => :scoped
       delegate :count, :average, :minimum, :maximum, :sum, :calculate, :to => :scoped
 
+      def inherited(child_class) #:nodoc:
+        # force attribute methods to be higher in inheritance hierarchy than other generated methods
+        child_class.generated_attribute_methods
+        child_class.generated_feature_methods
+        super
+      end
+
+      def generated_feature_methods
+        unless const_defined?(:GeneratedFeatureMethods, false)
+          include const_set(:GeneratedFeatureMethods, Module.new)
+        end
+        const_get(:GeneratedFeatureMethods)
+      end
+
       # Executes a custom SQL query against your database and returns all the results. The results will
       # be returned as an array with columns requested encapsulated as attributes of the model you call
       # this method from. If you call <tt>Product.find_by_sql</tt> then the results will be returned in

activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb

@@ -77,7 +77,7 @@ class DeveloperWithCounterSQL < ActiveRecord::Base
 
 class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
   fixtures :accounts, :companies, :categories, :posts, :categories_posts, :developers, :projects, :developers_projects,
-           :parrots, :pirates, :treasures, :price_estimates, :tags, :taggings
+           :parrots, :pirates, :parrots_pirates, :treasures, :price_estimates, :tags, :taggings
 
   def setup_data_for_habtm_case
     ActiveRecord::Base.connection.execute('delete from countries_treaties')
@@ -445,6 +445,26 @@ def test_destroy_all
     assert david.projects(true).empty?
   end
 
+  def test_destroy_associations_destroys_multiple_associations
+    george = parrots(:george)
+    assert !george.pirates.empty?
+    assert !george.treasures.empty?
+
+    assert_no_difference "Pirate.count" do
+      assert_no_difference "Treasure.count" do
+        george.destroy_associations
+      end
+    end
+
+    join_records = Parrot.connection.select_all("SELECT * FROM parrots_pirates WHERE parrot_id = #{george.id}")
+    assert join_records.empty?
+    assert george.pirates(true).empty?
+
+    join_records = Parrot.connection.select_all("SELECT * FROM parrots_treasures WHERE parrot_id = #{george.id}")
+    assert join_records.empty?
+    assert george.treasures(true).empty?
+  end
+
   def test_deprecated_push_with_attributes_was_removed
     jamis = developers(:jamis)
     assert_raise(NoMethodError) do

activerecord/test/cases/base_test.rb

@@ -69,6 +69,15 @@ def setup
 class BasicsTest < ActiveRecord::TestCase
   fixtures :topics, :companies, :developers, :projects, :computers, :accounts, :minimalistics, 'warehouse-things', :authors, :categorizations, :categories, :posts
 
+  def test_generated_methods_modules
+    modules = Computer.ancestors
+    assert modules.include?(Computer::GeneratedFeatureMethods)
+    assert_equal(Computer::GeneratedFeatureMethods, Computer.generated_feature_methods)
+    assert(modules.index(Computer.generated_attribute_methods) > modules.index(Computer.generated_feature_methods),
+           "generated_attribute_methods must be higher in inheritance hierarchy than generated_feature_methods")
+    assert_not_equal Computer.generated_feature_methods, Post.generated_feature_methods
+  end
+
   def test_column_names_are_escaped
     conn      = ActiveRecord::Base.connection
     classname = conn.class.name[/[^:]*$/]

activerecord/test/models/author.rb

@@ -128,7 +128,6 @@ def testing_proxy_target
   belongs_to :author_address,       :dependent => :destroy
   belongs_to :author_address_extra, :dependent => :delete, :class_name => "AuthorAddress"
 
-  has_many :post_categories, :through => :posts, :source => :categories
   has_many :category_post_comments, :through => :categories, :source => :post_comments
 
   has_many :misc_posts, :class_name => 'Post',