update constructor and Symbol.toStringTag properties on Iterator.prototype (#3970)

* update constructor and toStringTag properties on Iterator.prototype

* includes cannot be empty for some reason

* update description

* add esid

* updates

* freeze Iterator.prototype

* don't try to use real GeneratorPrototype for these tests

test/built-ins/Iterator/prototype/Symbol.toStringTag/prop-desc.js

@@ -1,20 +1,18 @@
 // Copyright (C) 2023 Michael Ficarra. All rights reserved.
 // This code is governed by the BSD license found in the LICENSE file.
 /*---
-es6id: 25.1.2.1
+esid: sec-iteratorprototype-@@tostringtag
 description: Property descriptor
 info: |
-    ES6 Section 17
-
-    Every other data property described in clauses 18 through 26 and in Annex
-    B.2 has the attributes { [[Writable]]: true, [[Enumerable]]: false,
-    [[Configurable]]: true } unless otherwise specified.
+  `Iterator.prototype[@@toStringTag]` is an accessor property with attributes { [[Enumerable]]: *false*, [[Configurable]]: *true* }
 features: [iterator-helpers]
 includes: [propertyHelper.js]
 ---*/
-verifyProperty(Iterator.prototype, Symbol.toStringTag, {
-  value: 'Iterator',
-  writable: true,
-  enumerable: false,
-  configurable: true,
-});
+verifyConfigurable(Iterator.prototype, Symbol.toStringTag);
+verifyNotEnumerable(Iterator.prototype, Symbol.toStringTag);
+
+let desc = Object.getOwnPropertyDescriptor(Iterator.prototype, Symbol.toStringTag);
+assert.sameValue(typeof desc.get, 'function');
+assert.sameValue(typeof desc.set, 'function');
+assert.sameValue(desc.value, undefined);
+assert.sameValue(desc.writable, undefined);

test/built-ins/Iterator/prototype/Symbol.toStringTag/weird-setter.js

@@ -0,0 +1,57 @@
+// Copyright (C) 2023 Michael Ficarra. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-set-iteratorprototype-@@tostringtag
+description: weird setter
+info: |
+  The value of the [[Get]] attribute is a built-in function that requires no arguments. It performs the following steps when called:
+    1. Return *"Iterator"*.
+
+  The value of the [[Set]] attribute is a built-in function that takes an argument _v_. It performs the following steps when called:
+    1. Perform ? SetterThatIgnoresPrototypeProperties(%Iterator.prototype%, %Symbol.toStringTag%, _v_).
+    2. Return *undefined*.
+features: [iterator-helpers]
+---*/
+
+let IteratorPrototype = Object.getPrototypeOf(Object.getPrototypeOf([][Symbol.iterator]()))
+
+let sentinel = 'a';
+
+let { get, set } = Object.getOwnPropertyDescriptor(Iterator.prototype, Symbol.toStringTag);
+
+assert.sameValue(Iterator.prototype[Symbol.toStringTag], 'Iterator');
+assert.sameValue(get.call(), 'Iterator');
+
+// 1. If _this_ is not an Object, then
+//   1. Throw a *TypeError* exception.
+assert.throws(() => set.call(undefined, ''));
+assert.throws(() => set.call(null, ''));
+assert.throws(() => set.call(true, ''));
+
+// 1. If _this_ is _home_, then
+//   1. NOTE: Throwing here emulates assignment to a non-writable data property on the _home_ object in strict mode code.
+//   1. Throw a *TypeError* exception.
+assert.throws(() => set.call(IteratorPrototype, ''));
+assert.throws(() => IteratorPrototype[Symbol.toStringTag] = '');
+
+assert.sameValue(Iterator.prototype[Symbol.toStringTag], 'Iterator');
+assert.sameValue(get.call(), 'Iterator');
+
+// 1. If _desc_ is *undefined*, then
+//   1. Perform ? CreateDataPropertyOrThrow(_this_, _p_, _v_).
+let FakeGeneratorPrototype = Object.create(IteratorPrototype);
+Object.freeze(IteratorPrototype);
+FakeGeneratorPrototype[Symbol.toStringTag] = sentinel;
+assert.sameValue(FakeGeneratorPrototype[Symbol.toStringTag], sentinel);
+
+assert.sameValue(Iterator.prototype[Symbol.toStringTag], 'Iterator');
+assert.sameValue(get.call(), 'Iterator');
+
+// 1. Else,
+//   1. Perform ? Set(_this_, _p_, _v_, *true*).
+let o = { [Symbol.toStringTag]: sentinel + 'a' };
+set.call(o, sentinel);
+assert.sameValue(o[Symbol.toStringTag], sentinel);
+
+assert.sameValue(Iterator.prototype[Symbol.toStringTag], 'Iterator');
+assert.sameValue(get.call(), 'Iterator');

test/built-ins/Iterator/prototype/constructor/prop-desc.js

@@ -0,0 +1,18 @@
+// Copyright (C) 2023 Michael Ficarra. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-iteratorprototype.constructor
+description: Property descriptor
+info: |
+  `Iterator.prototype.constructor` is an accessor property with attributes { [[Enumerable]]: *false*, [[Configurable]]: *true* }
+features: [iterator-helpers]
+includes: [propertyHelper.js]
+---*/
+verifyConfigurable(Iterator.prototype, 'constructor');
+verifyNotEnumerable(Iterator.prototype, 'constructor');
+
+let desc = Object.getOwnPropertyDescriptor(Iterator.prototype, 'constructor');
+assert.sameValue(typeof desc.get, 'function');
+assert.sameValue(typeof desc.set, 'function');
+assert.sameValue(desc.value, undefined);
+assert.sameValue(desc.writable, undefined);

test/built-ins/Iterator/prototype/constructor/weird-setter.js

@@ -0,0 +1,57 @@
+// Copyright (C) 2023 Michael Ficarra. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-set-iteratorprototype-constructor
+description: weird setter
+info: |
+  The value of the [[Get]] attribute is a built-in function that requires no arguments. It performs the following steps when called:
+    1. Return %Iterator%.
+
+  The value of the [[Set]] attribute is a built-in function that takes an argument _v_. It performs the following steps when called:
+    1. Perform ? SetterThatIgnoresPrototypeProperties(%Iterator.prototype%, *"constructor"*, _v_).
+    2. Return *undefined*.
+features: [iterator-helpers]
+---*/
+
+let IteratorPrototype = Object.getPrototypeOf(Object.getPrototypeOf([][Symbol.iterator]()))
+
+let sentinel = {};
+
+let { get, set } = Object.getOwnPropertyDescriptor(Iterator.prototype, 'constructor');
+
+assert.sameValue(Iterator.prototype.constructor, Iterator);
+assert.sameValue(get.call(), Iterator);
+
+// 1. If _this_ is not an Object, then
+//   1. Throw a *TypeError* exception.
+assert.throws(() => set.call(undefined, ''));
+assert.throws(() => set.call(null, ''));
+assert.throws(() => set.call(true, ''));
+
+// 1. If _this_ is _home_, then
+//   1. NOTE: Throwing here emulates assignment to a non-writable data property on the _home_ object in strict mode code.
+//   1. Throw a *TypeError* exception.
+assert.throws(() => set.call(IteratorPrototype, ''));
+assert.throws(() => IteratorPrototype.constructor = '');
+
+assert.sameValue(Iterator.prototype.constructor, Iterator);
+assert.sameValue(get.call(), Iterator);
+
+// 1. If _desc_ is *undefined*, then
+//   1. Perform ? CreateDataPropertyOrThrow(_this_, _p_, _v_).
+let FakeGeneratorPrototype = Object.create(IteratorPrototype);
+Object.freeze(IteratorPrototype);
+FakeGeneratorPrototype.constructor = sentinel;
+assert.sameValue(FakeGeneratorPrototype.constructor, sentinel);
+
+assert.sameValue(Iterator.prototype.constructor, Iterator);
+assert.sameValue(get.call(), Iterator);
+
+// 1. Else,
+//   1. Perform ? Set(_this_, _p_, _v_, *true*).
+let o = { constructor: sentinel + 'a' };
+set.call(o, sentinel);
+assert.sameValue(o.constructor, sentinel);
+
+assert.sameValue(Iterator.prototype.constructor, Iterator);
+assert.sameValue(get.call(), Iterator);