STI type is now updated when calling AR::Base.becomes on subclasses [#5953 state:resolved]

activerecord/lib/active_record/persistence.rb

@@ -96,6 +96,7 @@ module ActiveRecord
       became.instance_variable_set("@attributes_cache", @attributes_cache)
       became.instance_variable_set("@persisted", persisted?)
       became.instance_variable_set("@destroyed", destroyed?)
+      became.type = klass.name unless self.class.descends_from_active_record?
       became
     end
 

activerecord/test/cases/persistence_test.rb

@@ -241,6 +241,15 @@ class PersistencesTest < ActiveRecord::TestCase
     assert_nothing_raised { minimalistic.save }
   end
 
+  def test_update_sti_type
+    assert_instance_of Reply, topics(:second)
+
+    topic = topics(:second).becomes(Topic)
+    assert_instance_of Topic, topic
+    topic.save!
+    assert_instance_of Topic, Topic.find(topic.id)
+  end
+
   def test_delete
     topic = Topic.find(1)
     assert_equal topic, topic.delete, 'topic.delete did not return self'