setPluginManager example

$plugin_manager = $this->prophesize(PluginManagerInterface::class);
    $plugin_manager->createInstance($instance_id, ['id' => $instance_id])->willReturn($instance);

    // Also set up a container with the plugin manager so that we can assert     // that the plugin manager itself is also not serialized.     $container = TestKernel::setContainerWithKernel();
    $container->set('plugin.manager.foo', $plugin_manager->reveal());

    $entity_values = ['the_plugin_collection_config' => [$instance_id => ['foo' => 'original_value']]];
    $entity = new TestConfigEntityWithPluginCollections($entity_values, $this->entityTypeId);
    $entity->setPluginManager($plugin_manager->reveal());

    // After creating the entity, change the plugin configuration.     $instance->setConfiguration(['foo' => 'new_value']);

    // After changing the plugin configuration, the entity still has the     // original value.     $expected_plugin_config = [$instance_id => ['foo' => 'original_value']];
    $this->assertSame($expected_plugin_config, $entity->get('the_plugin_collection_config'));

    // Ensure the plugin collection and manager is not stored.     $vars = $entity->__sleep();