JSTests/test262/test/built-ins/Object/defineProperty/15.2.3.6-4-21.js

// Copyright (c) 2012 Ecma International.  All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.

/*---
info: |
    Step 4 of defineProperty calls the [[DefineOwnProperty]] internal method
    of O to define the property. For non-configurable properties, step 11.a.ii
    of [[DefineOwnProperty]] permits setting a getter if absent.
es5id: 15.2.3.6-4-21
description: >
    Object.defineProperty permits setting a getter (if absent) of
    non-configurable accessor properties(8.12.9 step 11.a.ii)
---*/

  var o = {};

  // create an accessor property; all other attributes default to false.
  // dummy setter
  var setter = function (x) {}
  var d1 = { set: setter };
  Object.defineProperty(o, "foo", d1);

  // now, trying to set the getter should succeed even though [[Configurable]]
  // on the original property will be false. Existing values of need to be preserved.
  var getter = undefined;
  var desc = { get: getter };

  Object.defineProperty(o, "foo", desc);
  var d2 = Object.getOwnPropertyDescriptor(o, "foo");

assert.sameValue(d2.get, getter, 'd2.get');
assert.sameValue(d2.set, setter, 'd2.set');
assert.sameValue(d2.configurable, false, 'd2.configurable');
assert.sameValue(d2.enumerable, false, 'd2.enumerable');