Revert "Revert "Merge pull request #8313 from alan/only_save_changed_has_one_objects""

This reverts commit e94e6c27af495a2460c811bb506459f1428dec6b.

Conflicts:
	activerecord/CHANGELOG.md

The original commit was reverted only to be safe since #14407 were reported.
We don't have any proof we added a regression with the original commit
so reverting it now will give us more problem.

Closes #14407

1 files changed, 13 insertions, 0 deletions

diff --git a/activerecord/test/cases/autosave_association_test.rb b/activerecord/test/cases/autosave_association_test.rb
index f7584c3a51..09892d50ba 100644
--- a/activerecord/test/cases/autosave_association_test.rb
+++ b/activerecord/test/cases/autosave_association_test.rb
@@ -683,10 +683,23 @@ class TestDestroyAsPartOfAutosaveAssociation < ActiveRecord::TestCase
       end
     end
 
+    @ship.pirate.catchphrase = "Changed Catchphrase"
+
     assert_raise(RuntimeError) { assert !@pirate.save }
     assert_not_nil @pirate.reload.ship
   end
 
+  def test_should_save_changed_has_one_changed_object_if_child_is_saved
+    @pirate.ship.name = "NewName"
+    assert @pirate.save
+    assert_equal "NewName", @pirate.ship.reload.name
+  end
+
+  def test_should_not_save_changed_has_one_unchanged_object_if_child_is_saved
+    @pirate.ship.expects(:save).never
+    assert @pirate.save
+  end
+
   # belongs_to
   def test_should_destroy_a_parent_association_as_part_of_the_save_transaction_if_it_was_marked_for_destroyal
     assert !@ship.pirate.marked_for_destruction?