To use with Panther (https://github.com/symfony/panther)

_README.md

A few test cases traits for PHPUnit that helps log users in your functional tests in Symfony

GetHttpClientTestTrait.php

<?php

declare(strict_types=1);

namespace Tests;

use Symfony\Bundle\FrameworkBundle\KernelBrowser;
use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase as BaseWebTestCase;
use Symfony\Component\BrowserKit\Cookie;
use Symfony\Component\Security\Core\Authentication\Token\UsernamePasswordToken;
use Symfony\Component\Security\Core\User\UserInterface;
use App\Repository\UserRepository;

trait GetHttpClientTestTrait
{
    protected function loginAsUser(KernelBrowser $client, string $username = 'lambda-user'): void
    {
        if (!$this instanceof BaseWebTestCase) {
            throw new \RuntimeException(\sprintf('Test case must extend %s to use Kernel features', BaseWebTestCase::class));
        }

        /** @var UserRepository $repo */
        $repo = static::$container->get(UserRepository::class);

        $user = $repo->findByUsernameOrEmail($username);

        if (!$user) {
            static::fail(\sprintf('Cannot find user "%s" to log in.', $username));
        }

        static::setToken($client, $user);
    }

    /**
     * @param string|UserInterface $username
     */
    protected static function setToken(KernelBrowser $client, $username = 'user', array $roles = ['ROLE_USER']): void
    {
        $firewallName = 'main';

        $session = $client->getContainer()->get('session');

        $token = new UsernamePasswordToken($username, null, $firewallName, $roles);
        $session->set('_security_'.$firewallName, \serialize($token));
        $session->save();

        $cookie = new Cookie($session->getName(), $session->getId());
        $client->getCookieJar()->set($cookie);
    }
}

PantherLoginTrait.php

<?php

declare(strict_types=1);

namespace Tests;

use Facebook\WebDriver\WebDriverBy;
use Facebook\WebDriver\WebDriverExpectedCondition;
use PHPUnit\Framework\Assert;
use Symfony\Component\Panther\Client;

trait PantherLoginTrait
{
    protected function loginAs(Client $client, string $username, string $plainPassword): void
    {
        $crawler = $client->request('GET', '/login');

        Assert::assertSame(200, $client->getInternalResponse()->getStatusCode());
        
        $htmlFormSelector = '#form_login';

        $driver = $client->getWebDriver();

        $driver->wait(2, 500)->until(WebDriverExpectedCondition::visibilityOfElementLocated(WebDriverBy::cssSelector($htmlFormSelector)));

        $form = $crawler->filter($htmlFormSelector)->form();

        $client->submit($form, [
            '_username' => $username,
            '_password' => $plainPassword,
        ]);

        $crawler = $client->request('GET', '/profile');

        Assert::assertSame('Update my profile', $crawler->filter('h1')->text());
    }
}