futtern/tests/Controller/HomeTest.php

<?php declare(strict_types=1);

namespace App\Tests\Controller;

use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;

final class HomeTest extends WebTestCase
{
    public function testSomething(): void
    {
        $client = static::createClient();
        $client->request('GET', '/');

        $this->assertResponseIsSuccessful();
        $this->assertSelectorTextContains('h1', 'Halloo');
    }
}