#3480217: Add Kernel test coverage of ApiLayoutController

Closes #3480217

tests/src/Kernel/ApiLayoutControllerTest.php

+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\experience_builder\Kernel;
+
+use Drupal\Core\Entity\FieldableEntityInterface;
+use Drupal\experience_builder\Controller\ApiLayoutController;
+use Drupal\KernelTests\KernelTestBase;
+use Drupal\node\Entity\Node;
+use Drupal\Tests\experience_builder\TestSite\XBTestSetup;
+use Symfony\Component\HttpFoundation\JsonResponse;
+
+/**
+ * @coversDefaultClass \Drupal\experience_builder\Controller\ApiLayoutController
+ * @group experience_builder
+ */
+class ApiLayoutControllerTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->container->get('module_installer')->install(['system']);
+    (new XBTestSetup())->setup();
+  }
+
+  public function test(): void {
+    $node = Node::load(1);
+    $controller = new ApiLayoutController();
+    assert($node instanceof FieldableEntityInterface);
+    $response = $controller($node);
+
+    $this->assertInstanceOf(JsonResponse::class, $response);
+    $json = json_decode($response->getContent() ?: '', TRUE);
+    $this->assertArrayHasKey('layout', $json);
+
+    $layout = $json['layout'];
+    $this->assertSame('root', $layout['uuid']);
+    $this->assertSame('root', $layout['nodeType']);
+    $this->assertSame('root', $layout['name']);
+    $this->assertArrayHasKey('children', $layout);
+
+    // @todo recurse through the tree
+    foreach ($layout['children'] as $child) {
+      $this->assertArrayHasKey('uuid', $child);
+      $this->assertArrayHasKey('nodeType', $child);
+      $this->assertArrayHasKey('type', $child);
+      $this->assertArrayHasKey('children', $child);
+
+      // @todo check non SDC components
+      $this->assertSame('component', $child['nodeType']);
+      $this->assertStringStartsWith('sdc.', $child['type']);
+    }
+  }
+
+}