namespace Drupal\Tests\drupalcon\Kernel;

use Drupal\drupalcon\Repository\ArticleRepository;
use Drupal\KernelTests\Core\Entity\EntityKernelTestBase;
use Drupal\Tests\node\Traits\NodeCreationTrait;

class ArticleRepositoryTest extends EntityKernelTestBase {

  public static $modules = [
    'drupalcon',
    'node',
  ];

// start test
  use NodeCreationTrait;

  /** @test */
  public function it_returns_blog_posts() {
    $this->createNode(['type' => 'article']);

    /** @var ArticleRepository */
    $repository = $this->container->get(ArticleRepository::class);

    $articles = $repository->getAll();

    $this->assertCount(1, $articles);
  }
// end test

}

---

// start output
.                                                                   1 / 1 (100%)

Time: 00:00.439, Memory: 6.00 MB

OK (1 test, 11 assertions)
// end output