Transport example

use Symfony\Component\Mailer\Transport\RoundRobinTransport;
use Symfony\Component\Mailer\Transport\TransportInterface;
use Symfony\Component\Mime\RawMessage;

class TransportTest extends TestCase
{
    /** * @dataProvider fromStringProvider */
    public function testFromString(string $dsn, TransportInterface $transport)
    {
        $transportFactory = new Transport([new DummyTransportFactory()]);

        $this->assertEquals($transport, $transportFactory->fromString($dsn));
    }

    public static function fromStringProvider(): iterable
    {
        $transportA = new DummyTransport('a');
        $transportB = new DummyTransport('b');

        yield 'simple transport' => [
            'dummy://a',