Adding property mapper for product eav attribute -> search weight.

app/code/Magento/CatalogSearch/Model/ResourceModel/Setup/PropertyMapper.php

@@ -0,0 +1,34 @@
+<?php
+declare(strict_types=1);
+
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\CatalogSearch\Model\ResourceModel\Setup;
+
+use Magento\Eav\Model\Entity\Setup\PropertyMapperAbstract;
+
+/**
+ * Class PropertyMapper
+ *
+ * @package Magento\CatalogSearch\Model\ResourceModel\Setup
+ */
+class PropertyMapper extends PropertyMapperAbstract
+{
+    /**
+     * Map input attribute properties to storage representation
+     *
+     * @param array $input
+     * @param int $entityTypeId
+     * @return array
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function map(array $input, $entityTypeId): array
+    {
+        return [
+            'search_weight' => $this->_getValue($input, 'search_weight', 1),
+        ];
+    }
+}

app/code/Magento/CatalogSearch/Test/Unit/Model/ResourceModel/Setup/PropertyMapperTest.php

@@ -0,0 +1,65 @@
+<?php
+declare(strict_types=1);
+
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\CatalogSearch\Test\Unit\Model\ResourceModel\Setup;
+
+use Magento\CatalogSearch\Model\ResourceModel\Setup\PropertyMapper;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Class PropertyMapperTest
+ *
+ * @package Magento\CatalogSearch\Test\Unit\Model\ResourceModel\Setup
+ */
+class PropertyMapperTest extends TestCase
+{
+    /**
+     * @var PropertyMapper
+     */
+    private $propertyMapper;
+
+    /**
+     * @return void
+     */
+    protected function setUp(): void
+    {
+        $this->propertyMapper = new PropertyMapper();
+    }
+
+    /**
+     * @return array
+     */
+    public function caseProvider(): array
+    {
+        return [
+            [
+                ['search_weight' => 9, 'something_other' => '3'],
+                ['search_weight' => 9]
+            ],
+            [
+                ['something' => 3],
+                ['search_weight' => 1]
+            ]
+        ];
+    }
+
+    /**
+     * @dataProvider caseProvider
+     *
+     * @test
+     *
+     * @param array $input
+     * @param array $result
+     * @return void
+     */
+    public function testMapCorrectlyMapsValue(array $input, array $result): void
+    {
+        //Second parameter doesn't matter as it is not used
+        $this->assertSame($result, $this->propertyMapper->map($input, 4));
+    }
+}

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

@@ -340,4 +340,11 @@
     <type name="Magento\Config\Model\Config">
         <plugin name="config_enable_eav_indexer" type="Magento\CatalogSearch\Plugin\EnableEavIndexer" />
     </type>
+    <type name="Magento\Eav\Model\Entity\Setup\PropertyMapper\Composite">
+        <arguments>
+            <argument name="propertyMappers" xsi:type="array">
+                <item name="catalog_search" xsi:type="string">Magento\CatalogSearch\Model\ResourceModel\Setup\PropertyMapper</item>
+            </argument>
+        </arguments>
+    </type>
 </config>