merge multiple nested associations

test/unit/active_model/serializer/associations_test.rb

@@ -14,6 +14,36 @@ module ActiveModel
         assert_equal([:comments],
                      another_inherited_serializer_klass._associations.keys)
       end
+      def test_multiple_nested_associations
+        parent = SelfReferencingUserParent.new(name: "The Parent")
+        child = SelfReferencingUser.new(name: "The child", parent: parent)
+        self_referencing_user_serializer = SelfReferencingUserSerializer.new(child)
+        result = self_referencing_user_serializer.as_json
+        expected_result = {
+          "self_referencing_user"=>{
+            :name=>"The child",
+            "type_id"=>child.type.object_id,
+            "parent_id"=>child.parent.object_id
+
+          },
+          "types"=>[
+            {
+              :name=>"N1",
+            },
+            {
+              :name=>"N2",
+            }
+          ],
+          "parents"=>[
+            {
+              :name=>"N1",
+              "type_id"=>child.parent.type.object_id,
+              "parent_id"=>nil
+            }
+          ]
+        }
+        assert_equal(expected_result, result)
+      end
     end
   end
 end