test/built-ins/Proxy/getOwnPropertyDescriptor/resultdesc-is-not-configurable-targetdesc-is-configurable.js


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// Copyright (C) 2015 the V8 project authors. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
es6id: 9.5.5
description: >
    Throws a TypeError exception if trap result is not configurable but target
    property descriptor is configurable.
info: |
    [[GetOwnProperty]] (P)

    ...
    22. If resultDesc.[[Configurable]] is false, then
        a. If targetDesc is undefined or targetDesc.[[Configurable]] is true,
        then
            i. Throw a TypeError exception.
    ...
---*/

var target = {
    bar: 1
};

var p = new Proxy(target, {
    getOwnPropertyDescriptor: function(t, prop) {
        var foo = {};

        Object.defineProperty(foo, "bar", {
            configurable: false,
            enumerable: true,
            value: 1
        });

        return Object.getOwnPropertyDescriptor(foo, prop);
    }
});

assert.throws(TypeError, function() {
    Object.getOwnPropertyDescriptor(p, "bar");
});