Fixing ordering of HABTM association deletion [#6191 state:resolved]

Signed-off-by: Santiago Pastorino <santiago@wyeworks.com>

activerecord/lib/active_record/associations.rb

@@ -1450,8 +1450,8 @@ module ActiveRecord
         include Module.new {
           class_eval <<-RUBY, __FILE__, __LINE__ + 1
             def destroy                     # def destroy
-              #{reflection.name}.clear      #   posts.clear
               super                         #   super
+              #{reflection.name}.clear      #   posts.clear
             end                             # end
           RUBY
         }

activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb

@@ -365,7 +365,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
   def test_removing_associations_on_destroy
     david = DeveloperWithBeforeDestroyRaise.find(1)
     assert !david.projects.empty?
-    assert_raise(RuntimeError) { david.destroy }
+    david.destroy
     assert david.projects.empty?
     assert DeveloperWithBeforeDestroyRaise.connection.select_all("SELECT * FROM developers_projects WHERE developer_id = 1").empty?
   end

activerecord/test/cases/habtm_destroy_order_test.rb

@@ -0,0 +1,17 @@
+require "cases/helper"
+require "models/lesson"
+require "models/student"
+
+class HabtmDestroyOrderTest < ActiveRecord::TestCase
+  test "may not delete a lesson with students" do
+    sicp = Lesson.new(:name => "SICP")
+    ben = Student.new(:name => "Ben Bitdiddle")
+    sicp.students << ben
+    sicp.save!
+    assert_raises LessonError do
+      assert_no_difference('Lesson.count') do
+        sicp.destroy
+      end
+    end
+  end
+end

activerecord/test/models/lesson.rb

@@ -0,0 +1,11 @@
+class LessonError < Exception
+end
+
+class Lesson < ActiveRecord::Base
+  has_and_belongs_to_many :students
+  before_destroy :ensure_no_students
+
+  def ensure_no_students
+    raise LessonError unless students.empty?
+  end
+end

activerecord/test/models/student.rb

@@ -0,0 +1,3 @@
+class Student < ActiveRecord::Base
+  has_and_belongs_to_many :lessons
+end

activerecord/test/schema/schema.rb

@@ -279,6 +279,15 @@ ActiveRecord::Schema.define do
     t.integer :version, :null => false, :default => 0
   end
 
+  create_table :lessons, :force => true do |t|
+    t.string :name
+  end
+
+  create_table :lessons_students, :id => false, :force => true do |t|
+    t.references :lesson
+    t.references :student
+  end
+
   create_table :line_items, :force => true do |t|
     t.integer :invoice_id
     t.integer :amount
@@ -509,6 +518,10 @@ ActiveRecord::Schema.define do
     t.string :sponsorable_type
   end
 
+  create_table :students, :force => true do |t|
+    t.string :name
+  end
+
   create_table :subscribers, :force => true, :id => false do |t|
     t.string :nick, :null => false
     t.string :name