Add lesson 4

- Add initial `PostNodeRepository`
- Move logic to Repository
- Inject `EntityTypeManagerInterface`
- Add `PostNodeRepositoryTest`
- Add failing test method
- Failing test: non-existent service
- The "node" entity type does not exist.
- Create posts
- Add assertions based on the `created` date
- Sort nodes before returning them
- Return values to reset array keys

web/modules/custom/example/example.services.yml

@@ -0,0 +1,4 @@
+services:
+  Drupal\example\Repository\PostNodeRepository:
+    arguments:
+      - '@entity_type.manager'

web/modules/custom/example/src/Controller/BlogPageController.php

@@ -3,12 +3,18 @@
 namespace Drupal\example\Controller;
 
 use Drupal\Core\Controller\ControllerBase;
+use Drupal\example\Repository\PostNodeRepository;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 
 class BlogPageController extends ControllerBase {
 
+  public function __construct(
+    private PostNodeRepository $postNodeRepository,
+  ) {
+  }
+
   public function __invoke(): array {
-    $nodeStorage = $this->entityTypeManager()->getStorage('node');
-    $nodes = $nodeStorage->loadMultiple();
+    $nodes = $this->postNodeRepository->findAll();
 
     $build = [];
     $build['content']['#theme'] = 'item_list';
@@ -19,4 +25,10 @@ class BlogPageController extends ControllerBase {
     return $build;
   }
 
+  public static function create(ContainerInterface $container): self {
+    return new self(
+      $container->get(PostNodeRepository::class),
+    );
+  }
+
 }

web/modules/custom/example/src/Repository/PostNodeRepository.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace Drupal\example\Repository;
+
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Drupal\node\NodeInterface;
+
+final class PostNodeRepository {
+
+  public function __construct(
+    private EntityTypeManagerInterface $entityTypeManager,
+  ) {
+  }
+
+  /**
+   * @return array<int, NodeInterface>
+   */
+  public function findAll(): array {
+    $nodeStorage = $this->entityTypeManager->getStorage('node');
+    $nodes = $nodeStorage->loadMultiple();
+
+    uasort($nodes, function (NodeInterface $a, NodeInterface $b): int {
+      return $a->getCreatedTime() <=> $b->getCreatedTime();
+    });
+
+    return array_values($nodes);
+  }
+
+}

web/modules/custom/example/tests/src/Kernel/PostNodeRepositoryTest.php

@@ -0,0 +1,54 @@
+<?php
+
+namespace Drupal\Tests\example\Kernel;
+
+use Drupal\Core\Datetime\DrupalDateTime;
+use Drupal\example\Repository\PostNodeRepository;
+use Drupal\KernelTests\Core\Entity\EntityKernelTestBase;
+use Drupal\node\NodeInterface;
+use Drupal\Tests\node\Traits\NodeCreationTrait;
+
+class PostNodeRepositoryTest extends EntityKernelTestBase {
+
+  use NodeCreationTrait;
+
+  protected static $modules = ['node', 'example'];
+
+  public function testPostsAreReturnedByCreatedDate(): void {
+    // Arrange.
+    $this->createNode([
+      'title' => 'Post one',
+      'created' => (new DrupalDateTime('-1 week'))->getTimestamp(),
+      'type' => 'post',
+    ]);
+
+    $this->createNode([
+      'title' => 'Post two',
+      'created' => (new DrupalDateTime('-8 days'))->getTimestamp(),
+      'type' => 'post',
+    ]);
+
+    $this->createNode([
+      'title' => 'Post three',
+      'created' => (new DrupalDateTime('yesterday'))->getTimestamp(),
+      'type' => 'post',
+    ]);
+
+    // Act.
+    $postRepository = $this->container->get(PostNodeRepository::class);
+    assert($postRepository instanceof PostNodeRepository);
+    $nodes = $postRepository->findAll();
+
+    // Assert.
+    self::assertCount(3, $nodes);
+
+    self::assertSame(
+      ['Post two', 'Post one', 'Post three'],
+      array_map(
+        fn (NodeInterface $node) => $node->label(),
+        $nodes
+      )
+    );
+  }
+
+}