JSTests/test262/test/built-ins/Object/defineProperty/15.2.3.6-4-151.js

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

/*---
es5id: 15.2.3.6-4-151
description: >
    Object.defineProperty - 'O' is an Array, 'name' is the length
    property of 'O', and the [[Value]] field of 'desc' is an Object
    with an own toString method and an inherited valueOf method
    (15.4.5.1 step 3.c), test that the inherited valueOf method is used
---*/

        var arrObj = [];
        var toStringAccessed = false;
        var valueOfAccessed = false;

        var proto = {
            valueOf: function () {
                valueOfAccessed = true;
                return 2;
            }
        };

        var ConstructFun = function () { };
        ConstructFun.prototype = proto;

        var child = new ConstructFun();
        child.toString = function () {
            toStringAccessed = true;
            return 3;
        };

        Object.defineProperty(arrObj, "length", {
            value: child
        });

assert.sameValue(arrObj.length, 2, 'arrObj.length');
assert.sameValue(toStringAccessed, false, 'toStringAccessed');
assert(valueOfAccessed, 'valueOfAccessed !== true');