Hi,

So, there are standard tests now for ES6!
http://samples.msdn.microsoft.com/ietestcenter/#javascript

I'd like to discuss some of the __proto__ tests at
http://samples.msdn.microsoft.com/ietestcenter/Javascript/testcases__proto_.html


# 3.1.1-10 Object.freeze(Object.prototype) disables __proto__

function testcase() {
   Object.freeze(Object.prototype);
   var a = new Object();
   a.__proto__ = { y: 2 };
   return a.y === undefined;
}

I'm not sure I see why this test should succeed. Freezing "a" should 
prevent its [[Prototype]] from being changed, but I don't see why it 
would be the case for Object.prototype.

(same for 3.1.1-9 for Object.seal)


# 3.1.1-11    [[DefineOwnProperty]] UnderScoreProtoEnabled is set to 
true when Object.prototype is set with default values

function testcase() {
     Object.defineProperty(Object.prototype, "__proto__", { writable: 
true, enumerable: false, configurable: true });

     var obj = {};
     obj.__proto__ = { x: 10 };
     return obj.x === 10;
}

I don't fully understand this test case. I think that overriding 
Object.prototype.__proto__ with a data attribute should remove its magic.

(same for 3.1.1-7, 3.1.2-4-1+bcd )


# 3.1.1-4    Object.prototype.__proto__ is data property with 
{writable:true, enumerable:false, configurable:true, value:null} attributes

function testcase() {
     var desc = Object.getOwnPropertyDescriptor(Object.prototype, 
"__proto__");
     return desc.writable === true &&
         desc.enumerable === false &&
         desc.configurable === true &&
         desc.value === null;
}

... hmm... I admire the sense of humor of whoever wrote that test.
TC39 Meeting notes from May 2013:
https://github.com/rwldrn/tc39-notes/blob/master/es6/2013-05/may-21.md#consensusresolution-5 
:
>  __proto__ is an accessor on Object.prototype.



# 3.1.1-6 Modification of Object.prototype.__proto__ causes 
UnderScoreEnabled to be set to false. Setting it to {}

function testcase() {
     Object.defineProperty(Object.prototype, "__proto__", {});

     var obj = new Object();
     obj.__proto__ = { y: 2 };
     return obj.y === undefined;

}

I believe the Object.defineProperty line is a no-op, so the test should 
fail.


# 3.1.2-2-14b  [[Put]] __proto__ with value {y:2} on window object

function testcase() {
     window.__proto__ = { y: 2 };
     return window.y === undefined;
}

window is not part of ECMAScript. This test might as well throw a 
ReferenceError.
As far as the global object, I don't think it's status on [[Prototype]] 
is very clear from a standard standpoint, so I would recommend not 
having tests for that.


I only looked at the tests failing in Firefox, there are probably other 
errors.
It would be good if the tests were reviewed carefully *before* becoming 
part of any sort of "conformance" test suite.

David

So, there are [standard tests now for ES6!](http://samples.msdn.microsoft.com/ietestcenter/#javascript)

I'd like to discuss some of [the `__proto__` tests](http://samples.msdn.microsoft.com/ietestcenter/Javascript/testcases__proto_.html).


# 3.1.1-10 `Object.freeze(Object.prototype)` disables `__proto__`

```js
function testcase() {
   Object.freeze(Object.prototype);
   var a = new Object();
   a.__proto__ = { y: 2 };
   return a.y === undefined;
}
```

I'm not sure I see why this test should succeed. Freezing "a" should 
prevent its [[Prototype]] from being changed, but I don't see why it 
would be the case for `Object.prototype`.

(same for 3.1.1-9 for `Object.seal`)

# 3.1.1-11 [[DefineOwnProperty]] UnderScoreProtoEnabled is set to true when `Object.prototype` is set with default values

```js
function testcase() {
     Object.defineProperty(Object.prototype, "__proto__", { writable: true, enumerable: false, configurable: true });

     var obj = {};
     obj.__proto__ = { x: 10 };
     return obj.x === 10;
}
```

I don't fully understand this test case. I think that overriding `Object.prototype.__proto__` with a data attribute should remove its magic.

(same for 3.1.1-7, 3.1.2-4-1+bcd )


# 3.1.1-4 `Object.prototype.__proto__` is data property with `{writable:true, enumerable:false, configurable:true, value:null}` attributes

```js
function testcase() {
     var desc = Object.getOwnPropertyDescriptor(Object.prototype, "__proto__");
     return desc.writable === true &&
         desc.enumerable === false &&
         desc.configurable === true &&
         desc.value === null;
}
```

... hmm... I admire the sense of humor of whoever wrote that test. [TC39 Meeting notes from May 2013](https://github.com/rwldrn/tc39-notes/blob/master/es6/2013-05/may-21.md#consensusresolution-5):

>  `__proto__` is an accessor on `Object.prototype`.

# 3.1.1-6 Modification of `Object.prototype.__proto__` causes UnderScoreEnabled to be set to false. Setting it to `{}`

```js
function testcase() {
     Object.defineProperty(Object.prototype, "__proto__", {});

     var obj = new Object();
     obj.__proto__ = { y: 2 };
     return obj.y === undefined;

}
```

I believe the `Object.defineProperty` line is a no-op, so the test should fail.


# 3.1.2-2-14b [[Put]] `__proto__` with value `{y:2}` on `window` object

```js
function testcase() {
     window.__proto__ = { y: 2 };
     return window.y === undefined;
}
```

`window` is not part of ECMAScript. This test might as well throw a `ReferenceError`.
As far as the global object, I don't think it's status on [[Prototype]] 
is very clear from a standard standpoint, so I would recommend not 
having tests for that.


I only looked at the tests failing in Firefox, there are probably other errors.
It would be good if the tests were reviewed carefully *before* becoming 
part of any sort of "conformance" test suite.

So, there are [standard tests now for ES6!](http://samples.msdn.microsoft.com/ietestcenter/#javascript)

I'd like to discuss some of [the `__proto__` tests](http://samples.msdn.microsoft.com/ietestcenter/Javascript/testcases__proto_.html).


# 3.1.1-10 `Object.freeze(Object.prototype)` disables `__proto__`

```js
function testcase() {
   Object.freeze(Object.prototype);
   var a = new Object();
   a.__proto__ = { y: 2 };
   return a.y === undefined;
}
```

I'm not sure I see why this test should succeed. Freezing "a" should 
prevent its [[Prototype]] from being changed, but I don't see why it 
would be the case for `Object.prototype`.

(same for 3.1.1-9 for `Object.seal`)

# 3.1.1-11 [[DefineOwnProperty]] UnderScoreProtoEnabled is set to true when `Object.prototype` is set with default values

```js
function testcase() {
     Object.defineProperty(Object.prototype, "__proto__", { writable: true, enumerable: false, configurable: true });

     var obj = {};
     obj.__proto__ = { x: 10 };
     return obj.x === 10;
}
```

I don't fully understand this test case. I think that overriding `Object.prototype.__proto__` with a data attribute should remove its magic.

(same for 3.1.1-7, 3.1.2-4-1+bcd )


# 3.1.1-4 `Object.prototype.__proto__` is data property with `{writable:true, enumerable:false, configurable:true, value:null}` attributes

```js
function testcase() {
     var desc = Object.getOwnPropertyDescriptor(Object.prototype, "__proto__");
     return desc.writable === true &&
         desc.enumerable === false &&
         desc.configurable === true &&
         desc.value === null;
}
```

... hmm... I admire the sense of humor of whoever wrote that test. [TC39 Meeting notes from May 2013](https://github.com/rwldrn/tc39-notes/blob/master/es6/2013-05/may-21.md#consensusresolution-5):

>  `__proto__` is an accessor on `Object.prototype`.

# 3.1.1-6 Modification of `Object.prototype.__proto__` causes UnderScoreEnabled to be set to false. Setting it to `{}`

```js
function testcase() {
     Object.defineProperty(Object.prototype, "__proto__", {});

     var obj = new Object();
     obj.__proto__ = { y: 2 };
     return obj.y === undefined;

}
```

I believe the `Object.defineProperty` line is a no-op, so the test should fail.


# 3.1.2-2-14b [[Put]] `__proto__` with value `{y:2}` on `window` object

```js
function testcase() {
     window.__proto__ = { y: 2 };
     return window.y === undefined;
}
```

`window` is not part of ECMAScript. This test might as well throw a `ReferenceError`.
As far as the global object, I don't think it's status on [[Prototype]] 
is very clear from a standard standpoint, so I would recommend not 
having tests for that.


I only looked at the tests failing in Firefox, there are probably other errors.
It would be good if the tests were reviewed carefully *before* becoming 
part of any sort of "conformance" test suite.