Fix/imposible customize product collection

app/code/Magento/Catalog/Block/Product/ListProduct.php

@@ -14,6 +14,7 @@
 use Magento\Catalog\Model\Layer\Resolver;
 use Magento\Catalog\Model\Product;
 use Magento\Catalog\Model\ResourceModel\Product\Collection;
+use Magento\Catalog\Model\Product\ProductList\CollectionLoader;
 use Magento\Catalog\Pricing\Price\FinalPrice;
 use Magento\Eav\Model\Entity\Collection\AbstractCollection;
 use Magento\Framework\App\ActionInterface;
@@ -68,12 +69,18 @@ class ListProduct extends AbstractProduct implements IdentityInterface
      */
     protected $categoryRepository;
 
+    /**
+     * @var CollectionLoader
+     */
+    protected $collectionLoader;
+
     /**
      * @param Context $context
      * @param PostHelper $postDataHelper
      * @param Resolver $layerResolver
      * @param CategoryRepositoryInterface $categoryRepository
      * @param Data $urlHelper
+     * @param CollectionLoader $collectionLoader
      * @param array $data
      */
     public function __construct(
@@ -82,12 +89,14 @@ public function __construct(
         Resolver $layerResolver,
         CategoryRepositoryInterface $categoryRepository,
         Data $urlHelper,
+        CollectionLoader $collectionLoader,
         array $data = []
     ) {
         $this->_catalogLayer = $layerResolver->get();
         $this->_postDataHelper = $postDataHelper;
         $this->categoryRepository = $categoryRepository;
         $this->urlHelper = $urlHelper;
+        $this->collectionLoader = $collectionLoader;
         parent::__construct(
             $context,
             $data
@@ -188,7 +197,7 @@ protected function _beforeToHtml()
 
         $this->addToolbarBlock($collection);
 
-        $collection->load();
+        $this->collectionLoader->load($collection);
 
         return parent::_beforeToHtml();
     }
@@ -463,7 +472,7 @@ private function initializeProductCollection()
         if ($origCategory) {
             $layer->setCurrentCategory($origCategory);
         }
-        
+
         $this->addToolbarBlock($collection);
 
         $this->_eventManager->dispatch(

app/code/Magento/Catalog/Block/Product/ProductList/Promotion.php

@@ -8,6 +8,7 @@
 use Magento\Catalog\Api\CategoryRepositoryInterface;
 use Magento\Catalog\Model\ResourceModel\Product\Collection;
 use Magento\Catalog\Model\ResourceModel\Product\CollectionFactory;
+use Magento\Catalog\Model\Product\ProductList\CollectionLoader;
 
 class Promotion extends \Magento\Catalog\Block\Product\ListProduct
 {
@@ -29,6 +30,7 @@ class Promotion extends \Magento\Catalog\Block\Product\ListProduct
      * @param \Magento\Catalog\Model\Layer\Resolver $layerResolver
      * @param CategoryRepositoryInterface $categoryRepository
      * @param \Magento\Framework\Url\Helper\Data $urlHelper
+     * @param CollectionLoader $collectionLoader
      * @param CollectionFactory $productCollectionFactory
      * @param array $data
      */
@@ -38,6 +40,7 @@ public function __construct(
         \Magento\Catalog\Model\Layer\Resolver $layerResolver,
         CategoryRepositoryInterface $categoryRepository,
         \Magento\Framework\Url\Helper\Data $urlHelper,
+        CollectionLoader $collectionLoader,
         CollectionFactory $productCollectionFactory,
         array $data = []
     ) {
@@ -48,6 +51,7 @@ public function __construct(
             $layerResolver,
             $categoryRepository,
             $urlHelper,
+            $collectionLoader,
             $data
         );
     }

app/code/Magento/Catalog/Block/Product/ProductList/Random.php

@@ -6,6 +6,7 @@
 namespace Magento\Catalog\Block\Product\ProductList;
 
 use Magento\Catalog\Api\CategoryRepositoryInterface;
+use Magento\Catalog\Model\Product\ProductList\CollectionLoader;
 
 /**
  * Catalog product random items block
@@ -32,6 +33,7 @@ class Random extends \Magento\Catalog\Block\Product\ListProduct
      * @param \Magento\Catalog\Model\Layer\Resolver $layerResolver
      * @param CategoryRepositoryInterface $categoryRepository
      * @param \Magento\Framework\Url\Helper\Data $urlHelper
+     * @param CollectionLoader $collectionLoader
      * @param \Magento\Catalog\Model\ResourceModel\Product\CollectionFactory $productCollectionFactory
      * @param array $data
      */
@@ -41,6 +43,7 @@ public function __construct(
         \Magento\Catalog\Model\Layer\Resolver $layerResolver,
         CategoryRepositoryInterface $categoryRepository,
         \Magento\Framework\Url\Helper\Data $urlHelper,
+        CollectionLoader $collectionLoader,
         \Magento\Catalog\Model\ResourceModel\Product\CollectionFactory $productCollectionFactory,
         array $data = []
     ) {
@@ -51,6 +54,7 @@ public function __construct(
             $layerResolver,
             $categoryRepository,
             $urlHelper,
+            $collectionLoader,
             $data
         );
     }

app/code/Magento/Catalog/Model/Product/ProductList/CollectionLoader.php

@@ -0,0 +1,28 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Magento\Catalog\Model\Product\ProductList;
+
+use Magento\Eav\Model\Entity\Collection\AbstractCollection;
+
+/**
+ * Class CollectionLoader
+ *
+ * @api
+ * @since 100.0.2
+ */
+class CollectionLoader
+{
+    /**
+     * @param AbstractCollection $collection
+     *
+     * @return AbstractCollection
+     */
+    public function load($collection)
+    {
+        $collection->load();
+        return $collection;
+    }
+}

app/code/Magento/Catalog/Test/Unit/Model/Product/ProductList/CollectionLoaderTest.php

@@ -0,0 +1,25 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\Catalog\Test\Unit\Model\Product\ProductList;
+
+use Magento\Framework\TestFramework\Unit\Helper\ObjectManager;
+use \Magento\Catalog\Model\Product\ProductList\CollectionLoader;
+
+class CollectionLoaderTest extends \PHPUnit\Framework\TestCase
+{
+    public function testGetOrder()
+    {
+        $collectionLoader = new CollectionLoader();
+        $mockedCollection = $this->getMockBuilder(\Magento\Catalog\Model\ResourceModel\Product\Collection::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+
+        $mockedCollection->expects($this->once())->method('load');
+
+        $collectionLoader->load($mockedCollection);
+    }
+}

app/code/Magento/Review/Model/Plugin/ProductList/CollectionLoader.php

@@ -0,0 +1,51 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\Review\Model\Plugin\ProductList;
+
+use Magento\Eav\Model\Entity\Collection\AbstractCollection;
+use Magento\Catalog\Model\Product\ProductList\CollectionLoader as Loader;
+use Magento\Review\Model\ReviewFactory;
+
+/**
+ * Class CollectionLoader
+ *
+ * @api
+ * @since 100.0.2
+ */
+class CollectionLoader
+{
+    /**
+     * Review model
+     *
+     * @var ReviewFactory
+     */
+    protected $reviewFactory;
+
+    /**
+     * @param ReviewFactory $reviewFactory
+     */
+    public function __construct(ReviewFactory $reviewFactory)
+    {
+        $this->reviewFactory = $reviewFactory;
+    }
+
+    /**
+     * Append review summary before rendering html
+     *
+     * @param Loader $subject
+     * @param AbstractCollection $result
+     * @return AbstractCollection
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function afterLoad(
+        Loader $subject,
+        AbstractCollection $result
+    ) {
+        $this->reviewFactory->create()->appendSummary($result);
+        return $result;
+    }
+}

app/code/Magento/Review/etc/di.xml

@@ -38,4 +38,7 @@
             </argument>
         </arguments>
     </type>
+    <type name="Magento\Catalog\Model\Product\ProductList\CollectionLoader">
+        <plugin name="ProductListCollectionLoader" type="Magento\Review\Model\Plugin\ProductList\CollectionLoader" sortOrder="1" />
+    </type>
 </config>

app/code/Magento/Review/etc/frontend/events.xml

@@ -9,7 +9,4 @@
     <event name="tag_tag_product_collection_load_after">
         <observer name="review" instance="Magento\Review\Observer\TagProductCollectionLoadAfterObserver" shared="false" />
     </event>
-    <event name="catalog_block_product_list_collection">
-        <observer name="review" instance="Magento\Review\Observer\CatalogBlockProductCollectionBeforeToHtmlObserver" shared="false" />
-    </event>
 </config>