test ListFeaturedPosts use case

backend/tests/Unit/Post/UseCases/ListFeaturedPostsTest.php

@@ -0,0 +1,71 @@
+<?php
+
+namespace Tests\Unit\Post\UseCases;
+
+use App\Post\CreatePostDto;
+use App\Post\Post;
+use App\Post\UseCases\ListFeaturedPosts\ListFeaturedPosts;
+use DateTimeImmutable;
+use DateTimeZone;
+use Tests\Fakes\FakePostRepository;
+use Tests\TestCase;
+
+class ListFeaturedPostsTest extends TestCase
+{
+    private FakePostRepository $postRepo;
+
+    private ListFeaturedPosts $useCase;
+
+    private DateTimeImmutable $now;
+
+    protected function setUp(): void
+    {
+        $this->now = new DateTimeImmutable(
+            '2026-05-06T12:00:00',
+            new DateTimeZone('UTC'),
+        );
+        $this->postRepo = new FakePostRepository;
+        $this->useCase = new ListFeaturedPosts($this->postRepo);
+    }
+
+    private function seedFeaturedPost(string $title, ?int $slot): Post
+    {
+        $post = $this->postRepo->create(new CreatePostDto(
+            userId: 1,
+            title: $title,
+            body: 'B',
+            createdAt: $this->now,
+        ));
+        if ($slot === null) {
+            return $post;
+        }
+
+        return $this->postRepo->update(new Post(
+            id: $post->getId(),
+            userId: $post->getUserId(),
+            title: $post->getTitle(),
+            body: $post->getBody(),
+            createdAt: $post->getCreatedAt(),
+            featureSlot: $slot,
+        ));
+    }
+
+    public function test_returns_empty_when_none_featured(): void
+    {
+        $this->seedFeaturedPost('not featured', null);
+        $this->assertSame([], $this->useCase->execute());
+    }
+
+    public function test_returns_featured_posts_in_slot_order(): void
+    {
+        $this->seedFeaturedPost('slot-2', 2);
+        $this->seedFeaturedPost('slot-1', 1);
+        $this->seedFeaturedPost('not-featured', null);
+
+        $featured = $this->useCase->execute();
+
+        $this->assertCount(2, $featured);
+        $this->assertSame('slot-1', $featured[0]->getTitle());
+        $this->assertSame('slot-2', $featured[1]->getTitle());
+    }
+}