1 files changed, 15 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 115e06144e..7a6aba6a6b 100644
--- a/activerecord/test/cases/associations/has_many_through_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_through_associations_test.rb
@@ -77,6 +77,21 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     end
   end
 
+  def test_add_two_instance_and_then_deleting
+    post   = posts(:thinking)
+    person = people(:david)
+
+    post.people << person
+    post.people << person
+
+    counts = ['post.people.count', 'post.people.to_a.count', 'post.readers.count', 'post.readers.to_a.count']
+    assert_difference counts, -2 do
+      post.people.delete(person)
+    end
+
+    assert !post.people.reload.include?(person)
+  end
+
   def test_associating_new
     assert_queries(1) { posts(:thinking) }
     new_person = nil # so block binding catches it