Fix issue 16315: Fix code standard & write unit test

Author: tna274

app/code/Magento/Catalog/Model/Indexer/Product/Flat/Action/Row.php

@@ -85,15 +85,7 @@ public function execute($id = null)
         $ids = [$id];
         $linkField = $this->metadataPool->getMetadata(ProductInterface::class)->getLinkField();
 
-        $select = $this->_connection->select();
-        $select->from(['e' => $this->_productIndexerHelper->getTable('store')], ['e.store_id'])
-            ->where('c.product_id = ' . $id)
-            ->joinLeft(
-                ['c' => $this->_productIndexerHelper->getTable('catalog_product_website')],
-                'e.website_id = c.website_id',
-                []
-            );
-        $storeIds = $this->_connection->fetchCol($select);
+        $storeIds = $this->getProductAvailableStores($id);
 
         $stores = $this->_storeManager->getStores();
         foreach ($stores as $store) {
@@ -143,4 +135,23 @@ public function execute($id = null)
 
         return $this;
     }
+
+    /**
+     * Get list store id where product is enable
+     *
+     * @param int $productId
+     * @return array
+     */
+    private function getProductAvailableStores($productId)
+    {
+        $select = $this->_connection->select();
+        $select->from(['e' => $this->_productIndexerHelper->getTable('store')], ['e.store_id'])
+            ->where('c.product_id = ' . $productId)
+            ->joinLeft(
+                ['c' => $this->_productIndexerHelper->getTable('catalog_product_website')],
+                'e.website_id = c.website_id',
+                []
+            );
+        return $this->_connection->fetchCol($select);
+    }
 }

app/code/Magento/Catalog/Test/Unit/Model/Indexer/Product/Flat/Action/RowTest.php

@@ -160,8 +160,24 @@ public function testExecuteWithExistingFlatTablesCreatesTables()
             ->willReturn('store_flat_table');
         $this->connection->expects($this->any())->method('isTableExists')->with('store_flat_table')
             ->willReturn(true);
+        $this->connection->expects($this->any())->method('fetchCol')
+            ->willReturn(['store_id_1']);
         $this->flatItemEraser->expects($this->once())->method('removeDeletedProducts');
         $this->flatTableBuilder->expects($this->never())->method('build')->with('store_id_1', ['product_id_1']);
         $this->model->execute('product_id_1');
     }
+
+    public function testExecuteWithExistingFlatTablesRemoveProductFromStore()
+    {
+        $this->productIndexerHelper->expects($this->any())->method('getFlatTableName')
+            ->willReturn('store_flat_table');
+        $this->connection->expects($this->any())->method('isTableExists')->with('store_flat_table')
+            ->willReturn(true);
+        $this->connection->expects($this->any())->method('fetchCol')
+            ->willReturn([1]);
+        $this->flatItemEraser->expects($this->once())->method('deleteProductsFromStore');
+        $this->flatItemEraser->expects($this->never())->method('removeDeletedProducts');
+        $this->flatTableBuilder->expects($this->never())->method('build')->with('store_id_1', ['product_id_1']);
+        $this->model->execute('product_id_1');
+    }
 }