Fix JRuby 'warning: (...) interpreted as grouped expression'

Author: bf4

test/action_controller/serialization_test.rb

@@ -214,14 +214,16 @@ def test_render_json_object_without_serializer
         get :render_json_object_without_serializer
 
         assert_equal 'application/json', @response.content_type
-        assert_equal ({error: 'Result is Invalid'}).to_json, @response.body
+        expected_body = {error: 'Result is Invalid'}
+        assert_equal expected_body.to_json, @response.body
       end
 
       def test_render_json_array_object_without_serializer
         get :render_json_array_object_without_serializer
 
         assert_equal 'application/json', @response.content_type
-        assert_equal ([{error: 'Result is Invalid'}]).to_json, @response.body
+        expected_body = [{error: 'Result is Invalid'}]
+        assert_equal expected_body.to_json, @response.body
       end
 
       def test_render_array_using_implicit_serializer