diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index b428605b9d..2e5b8cffa6 100644
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -577,6 +577,15 @@ class BasicsTest < ActiveRecord::TestCase
     assert_equal car.bulbs.includes(:car), Bulb.where(car_id: car.id), 'AssociationRelation should be comparable with Relation'
   end
 
+  def test_equality_of_collection_proxy_and_association_relation
+    car = Car.create!
+    car.bulbs.build
+    car.save
+
+    assert_equal car.bulbs, car.bulbs.includes(:car), 'CollectionProxy should be comparable with AssociationRelation'
+    assert_equal car.bulbs.includes(:car), car.bulbs, 'AssociationRelation should be comparable with CollectionProxy'
+  end
+
   def test_hashing
     assert_equal [ Topic.find(1) ], [ Topic.find(2).topic ] & [ Topic.find(1) ]
   end