diff --git a/app/code/Magento/Review/Block/Customer/View.php b/app/code/Magento/Review/Block/Customer/View.php
index 65e87940fd196..da5aff1f4d2f8 100644
--- a/app/code/Magento/Review/Block/Customer/View.php
+++ b/app/code/Magento/Review/Block/Customer/View.php
@@ -3,6 +3,7 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+
 namespace Magento\Review\Block\Customer;
 
 use Magento\Catalog\Model\Product;
@@ -202,7 +203,7 @@ public function dateFormat($date)
     }
 
     /**
-     * @return string
+     * @inheritDoc
      */
     protected function _toHtml()
     {
diff --git a/app/code/Magento/Review/Block/Product/ReviewRenderer.php b/app/code/Magento/Review/Block/Product/ReviewRenderer.php
index 59c385e4698eb..0fd6327e1f777 100644
--- a/app/code/Magento/Review/Block/Product/ReviewRenderer.php
+++ b/app/code/Magento/Review/Block/Product/ReviewRenderer.php
@@ -44,8 +44,8 @@ class ReviewRenderer extends \Magento\Framework\View\Element\Template implements
     /**
      * @param \Magento\Framework\View\Element\Template\Context $context
      * @param \Magento\Review\Model\ReviewFactory $reviewFactory
-     * @param ReviewSummaryFactory $reviewSummaryFactory
      * @param array $data
+     * @param ReviewSummaryFactory $reviewSummaryFactory
      */
     public function __construct(
         \Magento\Framework\View\Element\Template\Context $context,
@@ -54,7 +54,8 @@ public function __construct(
         ReviewSummaryFactory $reviewSummaryFactory = null
     ) {
         $this->_reviewFactory = $reviewFactory;
-        $this->reviewSummaryFactory = $reviewSummaryFactory ?? ObjectManager::getInstance()->get(ReviewSummaryFactory::class);
+        $this->reviewSummaryFactory = $reviewSummaryFactory ??
+            ObjectManager::getInstance()->get(ReviewSummaryFactory::class);
         parent::__construct($context, $data);
     }
 
@@ -94,7 +95,7 @@ public function getReviewsSummaryHtml(
             );
         }
 
-        if (!$product->getRatingSummary() && !$displayIfNoReviews) {
+        if (null === $product->getRatingSummary() && !$displayIfNoReviews) {
             return '';
         }
         // pick template among available
diff --git a/app/code/Magento/Review/Model/ResourceModel/Review/Summary.php b/app/code/Magento/Review/Model/ResourceModel/Review/Summary.php
index 153e0ae4da192..f18bc2094930a 100644
--- a/app/code/Magento/Review/Model/ResourceModel/Review/Summary.php
+++ b/app/code/Magento/Review/Model/ResourceModel/Review/Summary.php
@@ -79,15 +79,15 @@ public function reAggregate($summary)
      * Append review summary fields to product collection
      *
      * @param \Magento\Catalog\Model\ResourceModel\Product\Collection $productCollection
-     * @param $storeId
-     * @param $entityCode
+     * @param string $storeId
+     * @param string $entityCode
      * @return Summary
      * @throws \Magento\Framework\Exception\LocalizedException
      */
     public function appendSummaryFieldsToCollection(
         \Magento\Catalog\Model\ResourceModel\Product\Collection $productCollection,
-        $storeId,
-        $entityCode
+        string $storeId,
+        string $entityCode
     ) {
         if (!$productCollection->isLoaded()) {
             $summaryEntitySubSelect = $this->getConnection()->select();
@@ -99,7 +99,10 @@ public function appendSummaryFieldsToCollection(
                     'entity_code = ?',
                     $entityCode
                 );
-            $joinCond = new \Zend_Db_Expr("e.entity_id = review_summary.entity_pk_value AND review_summary.store_id = {$storeId} AND review_summary.entity_type = ({$summaryEntitySubSelect})");
+            $joinCond = new \Zend_Db_Expr(
+                "e.entity_id = review_summary.entity_pk_value AND review_summary.store_id = {$storeId}"
+                . " AND review_summary.entity_type = ({$summaryEntitySubSelect})"
+            );
             $productCollection->getSelect()
                 ->joinLeft(
                     ['review_summary' => $this->getMainTable()],
diff --git a/app/code/Magento/Review/Model/Review.php b/app/code/Magento/Review/Model/Review.php
index 2c8a794dbc0e1..0c581f570ef0c 100644
--- a/app/code/Magento/Review/Model/Review.php
+++ b/app/code/Magento/Review/Model/Review.php
@@ -318,7 +318,7 @@ public function appendSummary($collection)
             $entityIds[] = $item->getEntityId();
         }
 
-        if (sizeof($entityIds) == 0) {
+        if (count($entityIds) === 0) {
             return $this;
         }
 
diff --git a/app/code/Magento/Review/Model/ReviewSummary.php b/app/code/Magento/Review/Model/ReviewSummary.php
index c00294d40a93a..46851339ae6d7 100644
--- a/app/code/Magento/Review/Model/ReviewSummary.php
+++ b/app/code/Magento/Review/Model/ReviewSummary.php
@@ -10,6 +10,9 @@
 use Magento\Framework\Model\AbstractModel;
 use Magento\Review\Model\ResourceModel\Review\Summary\CollectionFactory as SummaryCollectionFactory;
 
+/**
+ * ReviewSummary model.
+ */
 class ReviewSummary
 {
     /**
@@ -17,6 +20,9 @@ class ReviewSummary
      */
     private $summaryCollectionFactory;
 
+    /**
+     * @param SummaryCollectionFactory $sumColFactory
+     */
     public function __construct(
         SummaryCollectionFactory $sumColFactory
     ) {
@@ -27,18 +33,20 @@ public function __construct(
      * Append review summary data to product
      *
      * @param AbstractModel $object
-     * @param $storeId
+     * @param int $storeId
      * @param int $entityType
      */
-    public function appendSummaryDataToObject(AbstractModel $object, $storeId, $entityType = 1): void
+    public function appendSummaryDataToObject(AbstractModel $object, int $storeId, int $entityType = 1): void
     {
         $summary = $this->summaryCollectionFactory->create()
             ->addEntityFilter($object->getId(), $entityType)
             ->addStoreFilter($storeId)
             ->getFirstItem();
-        $object->addData([
-            'reviews_count' => $summary->getData('reviews_count'),
-            'rating_summary' => $summary->getData('rating_summary')
-        ]);
+        $object->addData(
+            [
+                'reviews_count' => $summary->getData('reviews_count'),
+                'rating_summary' => $summary->getData('rating_summary')
+            ]
+        );
     }
 }
diff --git a/app/code/Magento/Review/Observer/CatalogProductListCollectionAppendSummaryFieldsObserver.php b/app/code/Magento/Review/Observer/CatalogProductListCollectionAppendSummaryFieldsObserver.php
index 5d29bb46a92eb..bb69284b5f0b8 100644
--- a/app/code/Magento/Review/Observer/CatalogProductListCollectionAppendSummaryFieldsObserver.php
+++ b/app/code/Magento/Review/Observer/CatalogProductListCollectionAppendSummaryFieldsObserver.php
@@ -12,6 +12,9 @@
 use Magento\Review\Model\ResourceModel\Review\SummaryFactory;
 use Magento\Store\Model\StoreManagerInterface;
 
+/**
+ * Append review summary to product list collection.
+ */
 class CatalogProductListCollectionAppendSummaryFieldsObserver implements ObserverInterface
 {
     /**
@@ -53,6 +56,7 @@ public function execute(EventObserver $observer)
             $this->storeManager->getStore()->getId(),
             \Magento\Review\Model\Review::ENTITY_PRODUCT_CODE
         );
+
         return $this;
     }
 }
diff --git a/app/code/Magento/Review/Test/Unit/Model/ReviewSummaryTest.php b/app/code/Magento/Review/Test/Unit/Model/ReviewSummaryTest.php
index ed998776961c4..9723ece0c4904 100644
--- a/app/code/Magento/Review/Test/Unit/Model/ReviewSummaryTest.php
+++ b/app/code/Magento/Review/Test/Unit/Model/ReviewSummaryTest.php
@@ -10,6 +10,9 @@
 use Magento\Framework\TestFramework\Unit\Helper\ObjectManager as ObjectManagerHelper;
 use PHPUnit\Framework\MockObject\MockObject;
 
+/**
+ * Test for Magento\Review\Model\ReviewSummary class.
+ */
 class ReviewSummaryTest extends \PHPUnit\Framework\TestCase
 {
     /**