michael@0: /*
michael@0:  * Any copyright is dedicated to the Public Domain.
michael@0:  * http://creativecommons.org/licenses/publicdomain/
michael@0:  */
michael@0: 
michael@0: function check(obj, name, value, readonly) {
michael@0:     // Start with a non-configurable, writable data property implemented via
michael@0:     // js::PropertyOp getter and setter.
michael@0:     var pd = Object.getOwnPropertyDescriptor(obj, name);
michael@0: 
michael@0:     assertEq(pd.configurable, false, "non-configurable " + name);
michael@0:     assertEq(pd.writable, !readonly, "writable " + name);
michael@0: 
michael@0:     try {
michael@0:         // Do not allow a transition from js::PropertyOp to writable js::Value
michael@0:         // data property.
michael@0:         Object.defineProperty(obj, name, {writable: true});
michael@0:         assertEq(0, 1);
michael@0:     } catch (e) {
michael@0:         assertEq('' + e, "TypeError: can't redefine non-configurable property '" + name + "'");
michael@0:     }
michael@0: 
michael@0:     if (!readonly) {
michael@0:         try {
michael@0:             // Do not allow the property denoted by name to become a true data
michael@0:             // property via a descriptor that preserves the native property's
michael@0:             // writable attribute.
michael@0:             Object.defineProperty(obj, name, {value: value});
michael@0:             assertEq(0, 1);
michael@0:         } catch (e) {
michael@0:             assertEq('' + e, "TypeError: can't redefine non-configurable property '" + name + "'");
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     try {
michael@0:         // Do not allow the property to be frozen at some bogus value.
michael@0:         Object.defineProperty(obj, name, {value: "bogus", writable: false});
michael@0:         assertEq(0, 1);
michael@0:     } catch (e) {
michael@0:         assertEq('' + e, "TypeError: can't redefine non-configurable property '" + name + "'");
michael@0:     }
michael@0: 
michael@0:     // Now make name non-writable.
michael@0:     Object.defineProperty(obj, name, {writable: false})
michael@0: 
michael@0:     // Assert that the right getter result "stuck".
michael@0:     assertEq(obj[name], value);
michael@0: 
michael@0:     // Test that it is operationally non-writable now.
michael@0:     obj[name] = "eek!";
michael@0:     assertEq(obj[name], value);
michael@0: }
michael@0: 
michael@0: check(Object, 'caller', null, false);
michael@0: check(Object, 'arguments', null, false);
michael@0: 
michael@0: // Reset RegExp.leftContext to the empty string.
michael@0: /x/.test('x');
michael@0: 
michael@0: var d = Object.getOwnPropertyDescriptor(RegExp, "leftContext");
michael@0: assertEq(d.set, undefined);
michael@0: assertEq(typeof d.get, "function");
michael@0: assertEq(d.enumerable, true);
michael@0: assertEq(d.configurable, false);
michael@0: assertEq(d.get.call(RegExp), "");
michael@0: 
michael@0: reportCompare(0, 0, "ok");