fix validation of iterators .next() results an objects in Iterator.{ zip, zipKeyed } polyfills

Author: zloirock

CHANGELOG.md

@@ -18,6 +18,7 @@
 - Fixed order of arguments validation in `Array.prototype.flat` polyfill
 - Fixed handling strings as iterables in `Iterator.{ zip, zipKeyed }` polyfills
 - Fixed some cases of iterators closing in `Iterator.{ zip, zipKeyed }` polyfills
+- Fixed validation of iterators `.next()` results an objects in `Iterator.{ zip, zipKeyed }` polyfills
 - Fixed a lack of early error in `Iterator.concat` polyfill on primitive as an iterator
 - Fixed iterator closing in `Set.prototype.{ isDisjointFrom, isSupersetOf }` polyfill
 - Fixed (updated following the final spec) one more case `Set.prototype.difference` polyfill with updating `this`

packages/core-js/internals/iterator-zip.js

@@ -1,6 +1,7 @@
 'use strict';
 var call = require('../internals/function-call');
 var uncurryThis = require('../internals/function-uncurry-this');
+var anObject = require('../internals/an-object');
 var createIteratorProxy = require('../internals/iterator-create-proxy');
 var iteratorCloseAll = require('../internals/iterator-close-all');
 
@@ -31,7 +32,7 @@ var IteratorProxy = createIteratorProxy(function () {
       result = padding[i];
     } else {
       try {
-        result = call(iter.next, iter.iterator);
+        result = anObject(call(iter.next, iter.iterator));
         done = result.done;
         result = result.value;
       } catch (error) {
@@ -54,7 +55,7 @@ var IteratorProxy = createIteratorProxy(function () {
           for (var k = 1; k < iterCount; k++) {
             // eslint-disable-next-line max-depth -- specification case
             try {
-              open = call(iters[k].next, iters[k].iterator);
+              open = anObject(call(iters[k].next, iters[k].iterator));
               openDone = open.done;
               open = open.value;
             } catch (error) {

tests/unit-global/esnext.iterator.zip.js

@@ -157,4 +157,15 @@ QUnit.test('Iterator.zip', assert => {
 
   assert.throws(() => zip(['hello', [1, 2, 3]]), TypeError, 'rejects string iterables');
   assert.throws(() => zip([42, [1, 2, 3]]), TypeError, 'rejects number iterables');
+  {
+    // iterator-zip: .next() result must be validated as an object
+    const primitiveNextIter = {
+      [Symbol.iterator]() {
+        return { next() { return 42; } };
+      },
+    };
+    const normalIter = [1, 2, 3];
+    const zipped = zip([primitiveNextIter, normalIter]);
+    assert.throws(() => zipped.next(), TypeError, 'throws on non-object .next() result');
+  }
 });

tests/unit-pure/esnext.iterator.zip.js

@@ -157,4 +157,15 @@ QUnit.test('Iterator.zip', assert => {
 
   assert.throws(() => zip(['hello', [1, 2, 3]]), TypeError, 'rejects string iterables');
   assert.throws(() => zip([42, [1, 2, 3]]), TypeError, 'rejects number iterables');
+  {
+    // iterator-zip: .next() result must be validated as an object
+    const primitiveNextIter = {
+      [Symbol.iterator]() {
+        return { next() { return 42; } };
+      },
+    };
+    const normalIter = [1, 2, 3];
+    const zipped = zip([primitiveNextIter, normalIter]);
+    assert.throws(() => zipped.next(), TypeError, 'throws on non-object .next() result');
+  }
 });