Test script to test container decoration

container-decorator-test.php

<?php

require "autoload.php";

use Drupal\Component\DependencyInjection\Dumper\PhpArrayDumper;
use Drupal\Core\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Reference;

/*

foo:
  class: \stdClass
  lazy: true

bar:
  public: false
  class: \stdClass
  decorates: foo
  arguments: ['@bar.inner']

-----

drupal.proxy_original_service.foo:
  class: \stdClass

foo:
  class: \FooProxyClass
  arguments: ['@service_container']

bar:
  public: false
  class: \stdClass
  decorates: foo
  arguments ['@bar.inner']

*/

$container = new ContainerBuilder();
$container->register('service_container', 'stdClass')
  ->setSynthetic(TRUE);
$container->register('drupal.proxy_original_service.foo', 'stdClass');

$container->register('foo', 'stdClass')
    ->addArgument(new Reference('service_container'));

$container->register('bar', 'stdClass')
    ->addArgument(new Reference('bar.inner'))
    ->setPublic(false)
    ->setDecoratedService('foo');

$container->compile();

$dumper = new PhpArrayDumper($container);
$definition = $dumper->getArray();

print_r($definition);

// ---------- OUTPUT

/*

Array
(
    [aliases] => Array
        (
        )

    [parameters] => Array
        (
        )

    [services] => Array
        (
            [service_container] => Array
                (
                    [class] => stdClass
                    [synthetic] => 1
                    [arguments_count] => 0
                )

            [drupal.proxy_original_service.foo] => Array
                (
                    [class] => stdClass
                    [arguments_count] => 0
                )

            [foo] => Array
                (
                    [class] => stdClass
                    [arguments] => Array
                        (
                            [0] => stdClass Object
                                (
                                    [type] => private_service
                                    [id] => private__0c4884282dbf6aa8e79e3b09da20c4c06c9456f6
                                    [value] => Array
                                        (
                                            [class] => stdClass
                                            [public] => 
                                            [arguments] => Array
                                                (
                                                    [0] => @service_container
                                                )

                                            [arguments_count] => 1
                                        )

                                    [shared] => 
                                )

                        )

                    [arguments_count] => 1
                )

        )

    [frozen] => 1
    [machine_format] => 
)

*/