LogTest.php

<?php

namespace Drupal\Tests\migrate\Kernel\Plugin;

use Drupal\KernelTests\KernelTestBase;
use Drupal\migrate\MigrateExecutableInterface;
use Drupal\migrate\Row;

/**
 * Tests the Log process plugin.
 *
 * @group migrate
 */
class LogTest extends KernelTestBase {
    
    /**
     * {@inheritdoc}
     */
    public static $modules = [
        'migrate',
    ];
    
    /**
     * Test the Log plugin.
     */
    public function testLog() {
        $plugin = \Drupal::service('plugin.manager.migrate.process')->createInstance('log');
        $executable = $this->prophesize(MigrateExecutableInterface::class)
            ->reveal();
        $row = new Row();
        $log_message = "Testing the log message";
        // Ensure the log is getting saved.
        $saved_message = $plugin->transform($log_message, $executable, $row, 'buffalo');
        $this->assertSame($log_message, $saved_message);
    }

}