test/built-ins/Object/defineProperty/15.2.3.6-4-17.js


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// 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 10.a.ii.1
    of [[DefineOwnProperty]] rejects changing the value of non-writable properties.
es5id: 15.2.3.6-4-17
description: >
    Object.defineProperty throws TypeError when changing value of
    non-writable non-configurable data properties
includes: [runTestCase.js]
---*/

function testcase() {
  var o = {};

  // create a data valued property; all other attributes default to false.
  var d1 = { value: 101 };
  Object.defineProperty(o, "foo", d1);

  // now, trying to change the value of "foo" should fail, since both
  // [[Configurable]] and [[Writable]] on the original property will be false.
  var desc = { value: 102 };

  try {
    Object.defineProperty(o, "foo", desc);
  }
  catch (e) {
    if (e instanceof TypeError) {
      // the property should remain unchanged.
      var d2 = Object.getOwnPropertyDescriptor(o, "foo");

      if (d2.value === 101 &&
          d2.writable === false &&
          d2.enumerable === false &&
          d2.configurable === false) {
        return true;
      }
    }
  }
 }
runTestCase(testcase);