ExecuteMigration.php

<?php

namespace Drupal\migrate_no_migrate_drupal_test\Controller;

use Drupal\Component\Plugin\Exception\InvalidPluginDefinitionException;
use Drupal\Core\Controller\ControllerBase;
use Drupal\migrate\MigrateExecutable;
use Drupal\migrate\Plugin\MigrationInterface;

/**
 * Custom controller to execute the test migrations.
 *
 * This controller class is required for the proper functional testing of
 * migration dependencies. Otherwise, the migration directly executed from the
 * functional test would use the functional test's class map and autoloader. The
 * functional test has all the classes available to it but the controller
 * does not.
 */
class ExecuteMigration extends ControllerBase {
    
    /**
     * Run the node_migration_no_migrate_drupal test migration.
     *
     * @return array
     *   A renderable array.
     */
    public function execute() {
        $migration_plugin_manager = \Drupal::service('plugin.manager.migration');
        $definitions = $migration_plugin_manager->getDefinitions();
        if ($definitions['node_migration_no_migrate_drupal']['label'] !== 'Node Migration No Migrate Drupal') {
            throw new InvalidPluginDefinitionException('node_migration_no_migrate_drupal');
        }
        $migrations = $migration_plugin_manager->createInstances('');
        $result = (new MigrateExecutable($migrations['node_migration_no_migrate_drupal']))->import();
        if ($result !== MigrationInterface::RESULT_COMPLETED) {
            throw new \RuntimeException('Migration failed');
        }
        return [
            '#type' => 'markup',
            '#markup' => 'Migration was successful.',
        ];
    }

}