src/third_party/mozjs-45/js/src/jit-test/tests/proxy/testDirectProxyValidateProperty3.js

load(libdir + "asserts.js");

/*
 * Throw a TypeError if the current descriptor is a data descriptor and the
 * descriptor returned by the trap is not, or vice versa, and the current
 * descriptor is non-configurable
 */
var target = {};
Object.defineProperty(target, 'foo', {
    value: 'bar',
    configurable: false
});
var caught = false;
assertThrowsInstanceOf(function () { 
    Object.getOwnPropertyDescriptor(new Proxy(target, {
        getOwnPropertyDescriptor: function (target, name) {
            return {
                get: function () {
                    return 'bar';
                },
                configurable: false
            };
        }
    }), 'foo');
}, TypeError);

var target = {};
Object.defineProperty(target, 'foo', {
    value: function () {
        return 'bar';
    },
    configurable: false
});
assertThrowsInstanceOf(function () { 
    Object.getOwnPropertyDescriptor(new Proxy(target, {
        getOwnPropertyDescriptor: function (target, name) {
            return {
                value: 'bar',
                configurable: false
            };
        }
    }), 'foo');
}, TypeError);