michael@0: load(libdir + "asserts.js");
michael@0: 
michael@0: /*
michael@0:  * Throw a TypeError if the trap returns a non-configurable descriptor for a
michael@0:  * non-existent property
michael@0:  */
michael@0: assertThrowsInstanceOf(function () {
michael@0:     Object.getOwnPropertyDescriptor(new Proxy({}, {
michael@0:         getOwnPropertyDescriptor: function (target, name) {
michael@0:             return {
michael@0:                 configurable: false
michael@0:             };
michael@0:         }
michael@0:     }), 'foo');
michael@0: }, TypeError);