Make sure to not add autosave callbacks multiple times. [#3575 state:resolved]

This makes sure that, in a HABTM association, only one join record is craeted.

2 files changed, 38 insertions, 0 deletions

diff --git a/activerecord/test/cases/autosave_association_test.rb b/activerecord/test/cases/autosave_association_test.rb
index 9164701601..803e5b25b1 100644
--- a/activerecord/test/cases/autosave_association_test.rb
+++ b/activerecord/test/cases/autosave_association_test.rb
@@ -31,11 +31,40 @@ class TestAutosaveAssociationsInGeneral < ActiveRecord::TestCase
     assert base.valid_keys_for_has_and_belongs_to_many_association.include?(:autosave)
   end
 
+  def test_should_not_add_the_same_callbacks_multiple_times_for_has_one
+    assert_no_difference_when_adding_callbacks_twice_for Pirate, :ship
+  end
+
+  def test_should_not_add_the_same_callbacks_multiple_times_for_belongs_to
+    assert_no_difference_when_adding_callbacks_twice_for Ship, :pirate
+  end
+
+  def test_should_not_add_the_same_callbacks_multiple_times_for_has_many
+    assert_no_difference_when_adding_callbacks_twice_for Pirate, :birds
+  end
+
+  def test_should_not_add_the_same_callbacks_multiple_times_for_has_and_belongs_to_many
+    assert_no_difference_when_adding_callbacks_twice_for Pirate, :parrots
+  end
+
   private
 
   def base
     ActiveRecord::Base
   end
+
+  def assert_no_difference_when_adding_callbacks_twice_for(model, association_name)
+    reflection = model.reflect_on_association(association_name)
+    assert_no_difference "callbacks_for_model(#{model.name}).length" do
+      model.send(:add_autosave_association_callbacks, reflection)
+    end
+  end
+
+  def callbacks_for_model(model)
+    model.instance_variables.grep(/_callbacks$/).map do |ivar|
+      model.instance_variable_get(ivar)
+    end.flatten
+  end
 end
 
 class TestDefaultAutosaveAssociationOnAHasOneAssociation < ActiveRecord::TestCase
diff --git a/activerecord/test/cases/nested_attributes_test.rb b/activerecord/test/cases/nested_attributes_test.rb
index 53fd168e1b..5367907fb7 100644
--- a/activerecord/test/cases/nested_attributes_test.rb
+++ b/activerecord/test/cases/nested_attributes_test.rb
@@ -371,6 +371,15 @@ module NestedAttributesOnACollectionAssociationTests
     assert_respond_to @pirate, association_setter
   end
 
+  def test_should_save_only_one_association_on_create
+    pirate = Pirate.create!({
+      :catchphrase => 'Arr',
+      association_getter => { 'foo' => { :name => 'Grace OMalley' } }
+    })
+
+    assert_equal 1, pirate.reload.send(@association_name).count
+  end
+
   def test_should_take_a_hash_with_string_keys_and_assign_the_attributes_to_the_associated_models
     @alternate_params[association_getter].stringify_keys!
     @pirate.update_attributes @alternate_params