MAGETWO-50893: No _Threshold_ message is displayed after buying product and its qty is not decreased

- fix tests

Author: mslabko

app/code/Magento/CatalogInventory/Test/Unit/Model/Config/Backend/ManagestockTest.php

@@ -3,7 +3,7 @@
  * Copyright © 2016 Magento. All rights reserved.
  * See COPYING.txt for license details.
  */
-namespace Magento\CatalogInventory\Test\Unit\Model;
+namespace Magento\CatalogInventory\Test\Unit\Model\Config\Backend;
 
 class ManagestockTest extends \PHPUnit_Framework_TestCase
 {

dev/tests/integration/testsuite/Magento/Catalog/_files/product_virtual.php

@@ -16,4 +16,9 @@
     ->setTaxClassId(0)
     ->setVisibility(\Magento\Catalog\Model\Product\Visibility::VISIBILITY_BOTH)
     ->setStatus(\Magento\Catalog\Model\Product\Attribute\Source\Status::STATUS_ENABLED)
-    ->save();
+    ->setStockData(
+        [
+            'qty' => 100,
+            'is_in_stock' => 1,
+        ]
+    )->save();

dev/tests/integration/testsuite/Magento/Paypal/_files/quote_payment_express.php

@@ -28,7 +28,12 @@
     ->setPrice(10)
     ->setVisibility(\Magento\Catalog\Model\Product\Visibility::VISIBILITY_BOTH)
     ->setStatus(\Magento\Catalog\Model\Product\Attribute\Source\Status::STATUS_ENABLED)
-    ->save();
+    ->setStockData(
+        [
+            'qty' => 100,
+            'is_in_stock' => 1,
+        ]
+    )->save();
 $product->load(1);
 
 $billingData = [

dev/tests/integration/testsuite/Magento/Sales/_files/quote.php

@@ -17,7 +17,12 @@
     ->setMetaDescription('meta description')
     ->setVisibility(\Magento\Catalog\Model\Product\Visibility::VISIBILITY_BOTH)
     ->setStatus(\Magento\Catalog\Model\Product\Attribute\Source\Status::STATUS_ENABLED)
-    ->save();
+    ->setStockData(
+        [
+            'qty' => 100,
+            'is_in_stock' => 1,
+        ]
+    )->save();
 
 $productRepository = \Magento\TestFramework\Helper\Bootstrap::getObjectManager()
     ->create('Magento\Catalog\Api\ProductRepositoryInterface');