Add default Stock in Data Install

app/code/Magento/InventoryCatalog/Setup/InstallData.php

@@ -0,0 +1,76 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\InventoryCatalog\Setup;
+
+use Magento\Framework\Setup\InstallDataInterface;
+use Magento\Framework\Setup\ModuleDataSetupInterface;
+use Magento\Framework\Setup\ModuleContextInterface;
+use Magento\InventoryApi\Api\Data\StockInterfaceFactory;
+use Magento\InventoryApi\Api\Data\StockInterface;
+use Magento\InventoryApi\Api\StockRepositoryInterface;
+use Magento\Framework\Api\DataObjectHelper;
+
+/**
+ * Class InstallData
+ */
+class InstallData implements InstallDataInterface
+{
+    /**
+     * @var StockRepositoryInterface
+     */
+    private $stockRepository;
+
+    /**
+     * @var StockInterfaceFactory
+     */
+    private $stockFactory;
+
+    /**
+     * @var DataObjectHelper
+     */
+    private $dataObjectHelper;
+
+    /**
+     * @param StockRepositoryInterface $stockRepository
+     * @param StockInterfaceFactory $stockFactory
+     * @param DataObjectHelper $dataObjectHelper
+     */
+    public function __construct(
+        StockRepositoryInterface $stockRepository,
+        StockInterfaceFactory $stockFactory,
+        DataObjectHelper $dataObjectHelper
+    ) {
+        $this->stockRepository = $stockRepository;
+        $this->stockFactory = $stockFactory;
+        $this->dataObjectHelper = $dataObjectHelper;
+    }
+
+    /**
+     * {@inheritdoc}
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function install(ModuleDataSetupInterface $setup, ModuleContextInterface $context)
+    {
+        $this->addDefaultStock();
+    }
+
+    /**
+     * Add default stock
+     *
+     * @return void
+     */
+    private function addDefaultStock()
+    {
+        $data = [
+            StockInterface::STOCK_ID => 1,
+            StockInterface::NAME => 'Default Stock'
+        ];
+        $source = $this->stockFactory->create();
+        $this->dataObjectHelper->populateWithArray($source, $data, StockInterface::class);
+        $this->stockRepository->save($source);
+    }
+}

app/code/Magento/InventoryCatalog/Test/Api/GetDefaultStockTest.php

@@ -0,0 +1,41 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\InventoryCatalog\Test\Api;
+
+use Magento\InventoryApi\Api\Data\StockInterface;
+use Magento\TestFramework\TestCase\WebapiAbstract;
+use Magento\Framework\Webapi\Rest\Request;
+
+/**
+ * Class GetDefaultStockTest
+ */
+class GetDefaultStockTest extends WebapiAbstract
+{
+    /**
+     * Test that default Stock is present after installation
+     */
+    public function testGetDefaultSource()
+    {
+        $defaultStockId = 1;
+        $serviceInfo = [
+            'rest' => [
+                'resourcePath' => '/V1/inventory/stock/' . $defaultStockId,
+                'httpMethod' => Request::HTTP_METHOD_GET,
+            ],
+            'soap' => [
+                'service' => 'inventoryApiStockRepositoryV1',
+                'operation' => 'inventoryApiStockRepositoryV1Get',
+            ],
+        ];
+        if (self::ADAPTER_REST == TESTS_WEB_API_ADAPTER) {
+            $stock = $this->_webApiCall($serviceInfo);
+        } else {
+            $stock = $this->_webApiCall($serviceInfo, ['stockId' => $defaultStockId]);
+        }
+        $this->assertEquals($defaultStockId, $stock[StockInterface::STOCK_ID]);
+    }
+}