Adding more tests and the code

src/Collection/Iterator/ZipIterator.php

@@ -0,0 +1,55 @@
+<?php
+/**
+ * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
+ * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ *
+ * Licensed under The MIT License
+ * For full copyright and license information, please see the LICENSE.txt
+ * Redistributions of files must retain the above copyright notice.
+ *
+ * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ * @link          http://cakephp.org CakePHP(tm) Project
+ * @since         3.0.0
+ * @license       http://www.opensource.org/licenses/mit-license.php MIT License
+ */
+namespace Cake\Collection\Iterator;
+
+use Cake\Collection\Collection;
+use Cake\Collection\CollectionInterface;
+use Cake\Collection\CollectionTrait;
+use MultipleIterator;
+
+/**
+ * Creates an iterator that returns elements grouped in pairs
+ *
+ * ### Example
+ *
+ * {{{
+ *  $iterator = new ZipIterator([1, 2], [3, 4]);
+ *  $iterator->toList(); // Returns [[1, 2], [3, 4]]
+ * }}}
+ */
+class ZipIterator extends MultipleIterator implements CollectionInterface
+{
+
+    use CollectionTrait;
+
+    protected $_firstIterator;
+
+    protected $_callback;
+
+    public function __construct(array $sets, $callable = null)
+    {
+        $sets = array_map(function ($items) {
+            return (new Collection($items))->unwrap();
+        }, $sets);
+
+        $this->_callback = $callable;
+        parent::__construct(MultipleIterator::MIT_NEED_ALL | MultipleIterator::MIT_KEYS_NUMERIC);
+
+        $this->_firstIterator = current($sets);
+        foreach ($sets as $set) {
+            $this->attachIterator($set);
+        }
+    }
+}

tests/TestCase/Collection/CollectionTest.php

@@ -1299,6 +1299,13 @@ public function testZip()
 
         $collection = new Collection([1, 2]);
         $zipped = $collection->zip([3]);
-        $this->assertEquals([[1, 3], [2, null]], $zipped->toList());
+        $this->assertEquals([[1, 3]], $zipped->toList());
+
+        $collection = new Collection([1, 2]);
+        $zipped = $collection->zip([3, 4], [5, 6], [7, 8], [9, 10, 11]);
+        $this->assertEquals([
+            [1, 3, 5, 7, 9],
+            [2, 4, 6, 8, 10]
+        ], $zipped->toList());
     }
 }