Symfony 4.1 KernelTestCase Repository ConnectionException

I'm following the symfony docs (https://symfony.com/doc/current/testing/doctrine.html) trying to test my repository classes against my MySQL database. The relevant code part is this:

class ProductRepositoryTest extends KernelTestCase
{
    /**
     * @var \Doctrine\ORM\EntityManager
     */
    private $entityManager;

    /**
     * {@inheritDoc}
     */
    protected function setUp()
    {
        $kernel = self::bootKernel();

        $this->entityManager = $kernel->getContainer()
            ->get('doctrine')
            ->getManager();
    }

    public function testSearchByCategoryName()
    {
        $products = $this->entityManager
            ->getRepository(Product::class)
            ->searchByCategoryName('foo')
        ;

        $this->assertCount(1, $products);
    }

    /**
     * {@inheritDoc}
     */
    protected function tearDown()
    {
        parent::tearDown();

        $this->entityManager->close();
        $this->entityManager = null; // avoid memory leaks
    }
}

When I execute the testclass with PhpUnit I get a Doctrine\DBAL\Exception\ConnectionException with the message: "An exception occurred in driver: SQLSTATE[HY000] [1045] Access denied for user 'root'@'localhost' (using password: NO)".

I stored my database connection data in the DATABASE_URL in the .env file and the connection works fine when executing: bin/console doctrine:migrations:migrate

But it seems this configuration is not used for testing (because 'NO' is not my password in the .env file). Do I have to store the connection configuration in another file for testing? And if yes, where do I have to store the configuration, so that it gets used in my testcase?

Thanks in advance for any help!

The .env file is only used in dev environment. If you're in prod or in test, it's not even read: https://symfony.com/doc/current/configuration.html#the-env-file-environment-variables. It's clear in some parts of the doc, but less in some others, which can be confusing.

In your case, you can check your config folder, more specifically probably under config/packages/doctrine.yaml and config/packages/parameters.yaml, and see how the DATABASE_URL is used (when it exists). From there, you can either hardcode that URL in config files specific to the test environment (creating a test subfolder under config/packages for instance), or you can give the proper DATABASE_URL environment variable to phpunit "manually" by using APP_ENV=... && bin/phpunit ....

Here's what a solution would look like in the first scenario :

# config/packages/test/doctrine.yaml
doctrine:
  dbal:
    url: 'mysql://db_user:db_password@127.0.0.1:3306/db_name'