michael@0: load(libdir + "asserts.js");
michael@0: 
michael@0: // Throw a TypeError if the trap sets a non-writable, non-configurable property
michael@0: var target = {};
michael@0: Object.defineProperty(target, 'foo', {
michael@0:     value: 'bar',
michael@0:     writable: false,
michael@0:     configurable: false
michael@0: });
michael@0: assertThrowsInstanceOf(function () {
michael@0:     new Proxy(target, {
michael@0:         set: function (target, name, val, receiver) {
michael@0:             return true;
michael@0:         }
michael@0:     })['foo'] = 'baz';
michael@0: }, TypeError);