rater/tests/Integration/Subject/AddSubjectTest.php

<?php

namespace App\Tests\Integration\Subject;

use App\Entity\Restaurant;
use App\Repository\SubjectRepository;
use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;

class AddSubjectTest extends WebTestCase
{
    public function testAddingNewSubject(): void
    {
        $client = static::createClient();
        $crawler = $client->request('GET', '/');

        $client->submitForm('form_save', ['form[name]' => 'Riviera']);

        $this->assertResponseRedirects();

        $crawler = $client->followRedirect();

        $subject = static::getContainer()
            ->get(SubjectRepository::class)
            ->findOneBy(['name' => 'Riviera']);

        $this->assertNotNull($subject);
        $this->assertInstanceOf(Restaurant::class, $subject);

        $this->assertSelectorTextContains('ul li', 'Riviera');
    }
}