From c2120582e4d27d2a64131820a46392af60f1e8b6 Mon Sep 17 00:00:00 2001
From: Fabian Schwahn <fabian.schwahn@gmail.com>
Date: Thu, 20 Apr 2017 11:10:06 +0200
Subject: [PATCH] Add regression test for setting inverse instances on normal &
 polymorphic relationships when building objects on new records

---
 .../associations/has_many_associations_test.rb     | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index e2f044c13964..40a0bea91b82 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -241,6 +241,13 @@ def test_create_from_association_with_nil_values_should_work
     assert_equal "defaulty", bulb.name
   end
 
+  def test_build_from_association_sets_inverse_instance
+    car = Car.new(name: "honda")
+
+    bulb = car.bulbs.build
+    assert_equal car, bulb.car
+  end
+
   def test_do_not_call_callbacks_for_delete_all
     car = Car.create(name: "honda")
     car.funky_bulbs.create!
@@ -2146,6 +2153,13 @@ def test_build_with_polymorphic_has_many_does_not_allow_to_override_type_and_id
     assert_equal "Post", tagging.taggable_type
   end
 
+  def test_build_from_polymorphic_association_sets_inverse_instance
+    post = Post.new
+    tagging = post.taggings.build
+
+    assert_equal post, tagging.taggable
+  end
+
   def test_dont_call_save_callbacks_twice_on_has_many
     firm = companies(:first_firm)
     contract = firm.contracts.create!