JSTests/test262/test/intl402/Date/prototype/toLocaleString/default-options-object-prototype.js

// Copyright (C) 2017 Daniel Ehrenberg. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.

/*---
esid: sec-todatetimeoptions
description: >
  Monkey-patching Object.prototype does not change the default
  options for DateTimeFormat as a null prototype is used.
info: |
  ToDateTimeOptions ( options, required, defaults )

  1. If options is undefined, let options be null; otherwise let options be ? ToObject(options).
  1. Let options be ObjectCreate(options).
---*/

if (new Intl.DateTimeFormat("en").resolvedOptions().locale === "en") {
  Object.prototype.year = "2-digit";
  assert.notSameValue(new Date().toLocaleString("en").length, 2);
}