Connection.php

<?php

namespace Drupal\driver_test\Driver\Database\DrivertestMysqlDeprecatedVersion;

include_once dirname(__DIR__, 8) . '/mysql/src/Driver/Database/mysql/Connection.php';
use Drupal\mysql\Driver\Database\mysql\Connection as CoreConnection;

/**
 * MySQL test implementation of \Drupal\Core\Database\Connection.
 */
class Connection extends CoreConnection {
    
    /**
     * Hardcoded database server version.
     *
     * Faking that we are on a deprecated database.
     *
     * @var string
     */
    protected $databaseVersion = '10.2.31-MariaDB-1:10.2.31+maria~bionic-log';
    
    /**
     * {@inheritdoc}
     */
    public function driver() {
        return 'DrivertestMysqlDeprecatedVersion';
    }
    
    /**
     * {@inheritdoc}
     */
    public function isMariaDb() : bool {
        return TRUE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function version() {
        return $this->databaseVersion;
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getServerVersion() : string {
        return $this->databaseVersion;
    }

}