UnusedTagsPass example

$this->addCompilerPassIfExists($container, AddMimeTypeGuesserPass::class);
        $this->addCompilerPassIfExists($container, AddScheduleMessengerPass::class);
        $this->addCompilerPassIfExists($container, MessengerPass::class);
        $this->addCompilerPassIfExists($container, HttpClientPass::class);
        $this->addCompilerPassIfExists($container, AddAutoMappingConfigurationPass::class);
        $container->addCompilerPass(new RegisterReverseContainerPass(true));
        $container->addCompilerPass(new RegisterReverseContainerPass(false), PassConfig::TYPE_AFTER_REMOVING);
        $container->addCompilerPass(new RemoveUnusedSessionMarshallingHandlerPass());

        if ($container->getParameter('kernel.debug')) {
            $container->addCompilerPass(new AddDebugLogProcessorPass(), PassConfig::TYPE_BEFORE_OPTIMIZATION, 2);
            $container->addCompilerPass(new UnusedTagsPass(), PassConfig::TYPE_AFTER_REMOVING);
            $container->addCompilerPass(new ContainerBuilderDebugDumpPass(), PassConfig::TYPE_BEFORE_REMOVING, -255);
            $container->addCompilerPass(new CacheCollectorPass(), PassConfig::TYPE_BEFORE_REMOVING);
        }
    }

    private function addCompilerPassIfExists(ContainerBuilder $container, string $class, string $type = PassConfig::TYPE_BEFORE_OPTIMIZATION, int $priority = 0): void
    {
        $container->addResource(new ClassExistenceResource($class));

        if (class_exists($class)) {
            $container->addCompilerPass(new $class(), $type, $priority);
        }

namespace Symfony\Bundle\FrameworkBundle\Tests\DependencyInjection\Compiler;

use PHPUnit\Framework\TestCase;
use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\UnusedTagsPass;
use Symfony\Component\DependencyInjection\ContainerBuilder;

class UnusedTagsPassTest extends TestCase
{
    public function testProcess()
    {
        $pass = new UnusedTagsPass();

        $container = new ContainerBuilder();
        $container->register('foo')
            ->addTag('kenrel.event_subscriber');
        $container->register('bar')
            ->addTag('kenrel.event_subscriber');

        $pass->process($container);

        $this->assertSame([sprintf('%s: Tag "kenrel.event_subscriber" was defined on service(s) "foo", "bar", but was never used. Did you mean "kernel.event_subscriber"?', UnusedTagsPass::class)], $container->getCompiler()->getLog());
    }