The Tor Browser / file revision

 /*

  * Any copyright is dedicated to the Public Domain.

  * http://creativecommons.org/licenses/publicdomain/

  */

 var gTestfile = 'proxy-array-target-length-definition.js';

 var BUGNUMBER = 905947;

 var summary =

   "Redefining an array's |length| property when redefining the |length| " +

   "property on a proxy with an array as target";

 print(BUGNUMBER + ": " + summary);

 /**************

  * BEGIN TEST *

  **************/

 var arr = [];

 var p = new Proxy(arr, {});

 // This really should throw a TypeError, but we're buggy just yet, and this

 // silently does nothing.

 Object.defineProperty(p, "length", { value: 17, configurable: true });

 // Same here.

 Object.defineProperty(p, "length", { value: 42, enumerable: true });

 // But at least we can check the property went unchanged.

 var pd = Object.getOwnPropertyDescriptor(p, "length");

 assertEq(pd.value, 0);

 assertEq(pd.writable, true);

 assertEq(pd.enumerable, false);

 assertEq(pd.configurable, false);

 var ad = Object.getOwnPropertyDescriptor(arr, "length");

 assertEq(ad.value, 0);

 assertEq(ad.writable, true);

 assertEq(ad.enumerable, false);

 assertEq(ad.configurable, false);

 /******************************************************************************/

 if (typeof reportCompare === "function")

   reportCompare(true, true);

 print("Tests complete");