silverstripe-framework/tests/php/ORM/DataExtensionTest/PlayerExtension.php

<?php

namespace SilverStripe\ORM\Tests\DataExtensionTest;

use SilverStripe\Dev\TestOnly;
use SilverStripe\ORM\DataExtension;
use SilverStripe\ORM\Tests\DataExtensionTest\Player;

class PlayerExtension extends DataExtension implements TestOnly
{

	public static function get_extra_config($class = null, $extensionClass = null, $args = null)
	{
		$config = array();

		// Only add these extensions if the $class is set to DataExtensionTest_Player, to
		// test that the argument works.
		if ($class == Player::class) {
			$config['db'] = array(
				'Address' => 'Text',
				'DateBirth' => 'Date',
				'Status' => "Enum('Shooter,Goalie')"
			);
			$config['defaults'] = array(
				'Status' => 'Goalie'
			);
		}

		return $config;
	}

}