CollectionAssociation#merge_target_lists should write to the underlying attributes when copying, rather than using the assignment method

1 files changed, 10 insertions, 0 deletions

diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index b149f5912f..0e33fa9c8e 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -1445,4 +1445,14 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
 
     assert_not_equal target.object_id, ary.object_id
   end
+
+  def test_merging_with_custom_attribute_writer
+    bulb = Bulb.new(:color => "red")
+    assert_equal "RED!", bulb.color
+
+    car = Car.create!
+    car.bulbs << bulb
+
+    assert_equal "RED!", car.bulbs.to_a.first.color
+  end
 end