1 files changed, 7 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 119e94b831..941e851aae 100644
--- a/activerecord/test/cases/associations/has_many_through_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_through_associations_test.rb
@@ -91,6 +91,13 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     end
   end
 
+  def test_concat
+    person = people(:david)
+    post   = posts(:thinking)
+    post.people.concat [person]
+    assert_equal 1, post.people.size
+    assert_equal 1, post.people(true).size
+  end
 
   def test_associate_existing_record_twice_should_add_to_target_twice
     post   = posts(:thinking)