use Symfony\Contracts\EventDispatcher\EventDispatcherInterface;

 class SomeClass
 {
     public function run(EventDispatcherInterface $eventDispatcher)
     {
-        $eventDispatcher->dispatch('event_name', new Event());
+        $eventDispatcher->dispatch(new Event(), 'event_name');
     }
 }

 use PHPUnit\Framework\TestCase;

 class SomeClass extends TestCase
 {
     public function test()
     {
-        $this->assertSame(200, $this->client->getResponse()->getStatusCode());
+        $this->assertResponseIsSuccessful();
     }
 }

 use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;

 final class SomeClass extends WebTestCase
 {
     public function test()
     {
-        $response = self::getClient()->getResponse();
-
-        $this->assertSame(301, $response->getStatusCode());
-        $this->assertSame('https://example.com', $response->headers->get('Location'));
+        $this->assertResponseStatusCodeSame(301);
+        $this->assertResponseRedirects('https://example.com');
     }
 }

 use Symfony\Bundle\FrameworkBundle\Controller\Controller;

 class BaseController extends Controller
 {
     function indexAction()
     {
-        $this->render('appBundle:Landing\Main:index.html.twig');
+        $this->render('@app/Landing/Main/index.html.twig');
     }
 }

-$currencyBundle = \Symfony\Component\Intl\Intl::getCurrencyBundle();
-
-$currencyNames = $currencyBundle->getCurrencyNames();
+$currencyNames = \Symfony\Component\Intl\Currencies::getNames();

-use Symfony\Bundle\TwigBundle\Loader\FilesystemLoader;
-use Symfony\Bundle\FrameworkBundle\Templating\Loader\TemplateLocator;
-use Symfony\Bundle\FrameworkBundle\Templating\TemplateNameParser;
+use Twig\Loader\FilesystemLoader;

-$filesystemLoader = new FilesystemLoader(new TemplateLocator(), new TemplateParser());
-$filesystemLoader->addPath(__DIR__ . '/some-directory');
+$fileSystemLoader = new FilesystemLoader([__DIR__ . '/some-directory']);

 use Symfony\Component\EventDispatcher\EventDispatcher;

 final class SomeEventDispatcher extends EventDispatcher
 {
     public function __construct()
     {
         $value = 1000;
+        parent::__construct();
     }
 }