Update unit test of Block/Product/ListProduct

modify return value of GetIteration on catCollectionMock

Author: mamsincl

app/code/Magento/Catalog/Test/Unit/Block/Product/ListProductTest.php

@@ -195,7 +195,7 @@ public function testGetIdentities()
 
         $this->catCollectionMock->expects($this->once())
             ->method('getIterator')
-            ->willReturn([$currentCategory]);
+            ->willReturn(new \ArrayIterator([$currentCategory]));
 
         $this->prodCollectionMock->expects($this->any())
             ->method('getIterator')