Make nested attributes behave like in 2.3.5 and add a sanity test for it with I18n.

activerecord/lib/active_record/autosave_association.rb

@@ -267,7 +267,7 @@ module ActiveRecord
       unless valid = association.valid?
         if reflection.options[:autosave]
           association.errors.each do |attribute, message|
-            attribute = "#{reflection.name}_#{attribute}"
+            attribute = "#{reflection.name}.#{attribute}"
             errors[attribute] << message if errors[attribute].empty?
           end
         else

activerecord/test/cases/autosave_association_test.rb

@@ -786,14 +786,14 @@ class TestAutosaveAssociationOnAHasOneAssociation < ActiveRecord::TestCase
   def test_should_automatically_validate_the_associated_model
     @pirate.ship.name = ''
     assert @pirate.invalid?
-    assert @pirate.errors[:ship_name].any?
+    assert @pirate.errors[:"ship.name"].any?
   end
 
   def test_should_merge_errors_on_the_associated_models_onto_the_parent_even_if_it_is_not_valid
     @pirate.ship.name   = nil
     @pirate.catchphrase = nil
     assert @pirate.invalid?
-    assert @pirate.errors[:ship_name].any?
+    assert @pirate.errors[:"ship.name"].any?
     assert @pirate.errors[:catchphrase].any?
   end
 
@@ -886,7 +886,7 @@ class TestAutosaveAssociationOnABelongsToAssociation < ActiveRecord::TestCase
   def test_should_automatically_validate_the_associated_model
     @ship.pirate.catchphrase = ''
     assert @ship.invalid?
-    assert @ship.errors[:pirate_catchphrase].any?
+    assert @ship.errors[:"pirate.catchphrase"].any?
   end
 
   def test_should_merge_errors_on_the_associated_model_onto_the_parent_even_if_it_is_not_valid
@@ -894,7 +894,7 @@ class TestAutosaveAssociationOnABelongsToAssociation < ActiveRecord::TestCase
     @ship.pirate.catchphrase = nil
     assert @ship.invalid?
     assert @ship.errors[:name].any?
-    assert @ship.errors[:pirate_catchphrase].any?
+    assert @ship.errors[:"pirate.catchphrase"].any?
   end
 
   def test_should_still_allow_to_bypass_validations_on_the_associated_model
@@ -961,7 +961,7 @@ module AutosaveAssociationOnACollectionAssociationTests
     @pirate.send(@association_name).each { |child| child.name = '' }
 
     assert !@pirate.valid?
-    assert_equal ["can't be blank"], @pirate.errors["#{@association_name}_name"]
+    assert_equal ["can't be blank"], @pirate.errors["#{@association_name}.name"]
     assert @pirate.errors[@association_name].empty?
   end
 
@@ -969,16 +969,32 @@ module AutosaveAssociationOnACollectionAssociationTests
     @pirate.send(@association_name).build(:name => '')
 
     assert !@pirate.valid?
-    assert_equal ["can't be blank"], @pirate.errors["#{@association_name}_name"]
+    assert_equal ["can't be blank"], @pirate.errors["#{@association_name}.name"]
     assert @pirate.errors[@association_name].empty?
   end
 
+  def test_should_default_invalid_error_from_i18n
+    I18n.backend.store_translations(:en, :activerecord => { :errors => { :models =>
+      { @association_name.to_s.singularize.to_sym => { :blank => "cannot be blank" } }
+    }})
+
+    @pirate.send(@association_name).build(:name => '')
+
+    assert !@pirate.valid?
+    assert_equal ["cannot be blank"], @pirate.errors["#{@association_name}.name"]
+    assert @pirate.errors[@association_name].empty?
+  ensure
+    I18n.backend.store_translations(:en, :activerecord => { :errors => { :models =>
+      { @association_name.to_s.singularize.to_sym => nil }
+    }})
+  end
+
   def test_should_merge_errors_on_the_associated_models_onto_the_parent_even_if_it_is_not_valid
     @pirate.send(@association_name).each { |child| child.name = '' }
     @pirate.catchphrase = nil
 
     assert !@pirate.valid?
-    assert_equal ["can't be blank"], @pirate.errors["#{@association_name}_name"]
+    assert_equal ["can't be blank"], @pirate.errors["#{@association_name}.name"]
     assert @pirate.errors[:catchphrase].any?
   end
 

activerecord/test/cases/nested_attributes_test.rb

@@ -592,7 +592,7 @@ module NestedAttributesOnACollectionAssociationTests
       assert_no_difference ['Man.count', 'Interest.count'] do
         man = Man.create(:name => 'John',
                          :interests_attributes => [{:topic=>'Cars'}, {:topic=>'Sports'}])
-        assert !man.errors[:interests_man].empty?
+        assert !man.errors[:"interests.man"].empty?
       end
     end
     # restore :inverse_of