Mock discovery in plugin manager

gistfile1.txt

<?php

namespace Drupal\Tests\list_predefined_options\Kernel;

use Drupal\Component\Plugin\Discovery\DiscoveryInterface;
use Drupal\Component\Plugin\Exception\InvalidPluginDefinitionException;
use Drupal\Core\DependencyInjection\ContainerBuilder;
use Drupal\Core\DependencyInjection\ServiceModifierInterface;
use Drupal\KernelTests\KernelTestBase;
use Drupal\list_predefined_options\ListOptionsManager;

/**
 * Test case class TODO.
 *
 * @group list_predefined_options
 */
class ListOptionsDefinitionTest extends KernelTestBase implements ServiceModifierInterface {

  /**
   * The modules to enable.
   *
   * @var array
   */
  protected static $modules = [
    'system',
    'user',
    'list_predefined_options',
  ];

  /**
   * {@inheritdoc}
   */
  protected function setUp(): void {
    parent::setUp();
  }

  public function alter(ContainerBuilder $container) {
    // Change the class of the plugin manager service.
    $original_service_definition = $container->getDefinition('plugin.manager.list_options');
    $original_service_definition->setClass(TestService::class);
  }

  /**
   * Tests the TODO.
   */
  public function testMyTest() {
    $manager = $this->container->get('plugin.manager.list_options');

    $discovery_mock = $this->prophesize(DiscoveryInterface::class);
    $discovery_mock->getDefinitions()->willReturn([
      'bad_plugin' => [
        'label' => 'Bad plugin',
      ],
    ]);
    $manager->setDiscovery($discovery_mock->reveal());

    $this->expectException(InvalidPluginDefinitionException::class);
    $this->container->get('plugin.manager.list_options')->getDefinitions();
  }

}

/**
 * Extend the plugin manager to allow us to set the discovery.
 */
class TestService extends ListOptionsManager {

   public function setDiscovery($discovery) {
    $this->discovery = $discovery;
   }

}