1 files changed, 8 insertions, 0 deletions
diff --git a/activerecord/test/cases/associations/has_many_through_associations_test.rb b/activerecord/test/cases/associations/has_many_through_associations_test.rb
index 8641584c0c..ad2aa99af5 100644
--- a/activerecord/test/cases/associations/has_many_through_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_through_associations_test.rb
@@ -1139,4 +1139,12 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     assert_equal 2, post.lazy_readers_unscope_skimmers.to_a.size
     assert_equal 2, post.lazy_people_unscope_skimmers.to_a.size
   end
+  
+  def test_has_many_through_add_with_sti_middle_relation
+    club = SuperClub.create!(name: 'Fight Club')
+    member = Member.create!(name: 'Tyler Durden')
+
+    club.members << member
+    assert_equal 1, SuperMembership.where(member_id: member.id, club_id: club.id).count
+  end
 end