Add graphql stitching test

Author: convenient

dev/tests/integration/testsuite/Magento/Framework/GraphQl/GraphQlSchemaStitching/GraphQlReaderTest.php

@@ -0,0 +1,67 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+declare(strict_types=1);
+
+namespace Magento\Framework\GraphQlSchemaStitching\Test\Unit;
+
+use Magento\Framework\GraphQlSchemaStitching\GraphQlReader;
+use Magento\Framework\ObjectManagerInterface;
+use Magento\Framework\TestFramework\Unit\Helper\ObjectManager;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+use Magento\Framework\Config\FileResolverInterface;
+use Magento\Framework\Config\FileIterator;
+use Magento\Framework\Component\ComponentRegistrar;
+
+/**
+ * Test of the stitching of graphql schemas together
+ */
+class GraphQlReaderTest extends TestCase
+{
+    /**
+     * Object Manager Instance
+     *
+     * @var ObjectManager
+     */
+    private $objectManager;
+
+    /**
+     * @var GraphQlReader|MockObject
+     */
+    private $graphQlReader;
+
+    protected function setUp(): void
+    {
+        /** @var ObjectManagerInterface $objectManager */
+        $this->objectManager = \Magento\TestFramework\Helper\Bootstrap::getObjectManager();
+
+        $this->graphQlReader = $this->objectManager->create(
+            GraphQlReader::class
+        );
+    }
+
+    /**
+     * This test ensures that the global graphql schemas have all the required dependencies and can be stitched together
+     *
+     * The $results variables contains the actual schema as it will be on a production site which will vary per each
+     * update of magento, so asserting the array matches the entire schema does not make full sense here as any change
+     * in graphql in any magento module would break the test.
+     *
+     * Testing this way means we do not need to store the module meta data that was introduced in
+     * https://github.com/magento/magento2/pull/28747 which means we can greatly improve the performance of this
+     */
+    public function testStitchGlobalGraphQLSchema()
+    {
+        $results = $this->graphQlReader->read('global');
+
+        $this->assertArrayHasKey('Price', $results);
+        $this->assertArrayHasKey('Query', $results);
+        $this->assertArrayHasKey('Mutation', $results);
+        $this->assertArrayHasKey('ProductInterface', $results);
+        $this->assertArrayHasKey('SimpleProduct', $results);
+    }
+}