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load(libdir + "asserts.js");
function testMapped(a) {
assertEq(arguments[0], 1);
Object.defineProperty(arguments, 0, {value: 23, writable: true, configurable: true});
assertEq(arguments[0], 23);
assertEq(a, 23);
a = 12;
assertEq(a, 12);
assertEq(arguments[0], 12);
Object.defineProperty(arguments, 0, {value: 9, writable: false, configurable: false});
assertEq(arguments[0], 9);
assertEq(a, 9);
a = 4;
assertEq(arguments[0], 9);
assertEq(a, 4);
}
for (var i = 0; i < 5; i++) {
testMapped(1);
}
function testAttributes(x) {
Object.defineProperty(arguments, 0, {enumerable:true,
writable:true,
configurable:true,
value: 4});
// Should inherit enumerable/configurable attributes.
Object.defineProperty(arguments, 0, {writable:true,
value: 8});
assertEq(JSON.stringify(Object.getOwnPropertyDescriptor(arguments, 0)),
'{"value":8,"writable":true,"enumerable":true,"configurable":true}');
assertEq(x, 8);
// Property becomes non-configurable.
Object.defineProperty(arguments, 0, {writable:true,
configurable:false,
value: 6});
assertEq(JSON.stringify(Object.getOwnPropertyDescriptor(arguments, 0)),
'{"value":6,"writable":true,"enumerable":true,"configurable":false}');
assertEq(x, 6);
// Can no longer make it non-enumerable.
assertThrowsInstanceOf(() => Object.defineProperty(arguments, 0, {writable:true,
configurable:false,
enumerable:false,
value: 6}),
TypeError);
// Can no longer make it configurable.
assertThrowsInstanceOf(() => Object.defineProperty(arguments, 0, {writable:true,
configurable:true,
value: 6}),
TypeError);
// Can still make it non-writable.
Object.defineProperty(arguments, 0, {writable:false,
enumerable:true,
configurable:false,
value: 3});
assertEq(x, 3);
// No longer a mapped property.
x = 5;
assertEq(arguments[0], 3);
// Can no longer make it writable.
assertThrowsInstanceOf(() => Object.defineProperty(arguments, 0, {writable:true,
enumerable:true,
configurable:false,
value: 5}),
TypeError);
assertEq(x, 5);
}
for (var i = 0; i < 5; i++) {
testAttributes(i);
}
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