JSTests/test262/test/built-ins/Object/defineProperty/15.2.3.6-4-15.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 configurable properties, step 9c of
    [[DefineOwnProperty]] permits changing the kind of a property.
es5id: 15.2.3.6-4-15
description: >
    Object.defineProperty permits changing accessor property to data
    property for configurable properties
---*/

  var o = {};

  // define an accessor property
  // dummy getter
  var getter = function () { return 1; }
  var d1 = { get: getter, configurable: true };
  Object.defineProperty(o, "foo", d1);

  // changing "foo" to be a data valued property should succeed, since
  // [[Configurable]] on the original property will be true. Existing
  // values of [[Configurable]] and [[Enumerable]] need to be preserved
  // and the rest need to be set to their default values.
  var desc = { value: 101 };
  Object.defineProperty(o, "foo", desc);
  var d2 = Object.getOwnPropertyDescriptor(o, "foo");

assert.sameValue(d2.value, 101, 'd2.value');
assert.sameValue(d2.writable, false, 'd2.writable');
assert.sameValue(d2.enumerable, false, 'd2.enumerable');
assert.sameValue(d2.configurable, true, 'd2.configurable');