silverstripe-framework/tests/php/Security/GroupTest/TestMember.php

<?php

namespace SilverStripe\Security\Tests\GroupTest;

use SilverStripe\Dev\TestOnly;
use SilverStripe\Forms\CheckboxSetField;
use SilverStripe\Forms\FieldList;
use SilverStripe\Forms\HiddenField;
use SilverStripe\ORM\DataObject;
use SilverStripe\Security\Group;
use SilverStripe\Security\Member;

class TestMember extends Member implements TestOnly
{
	private static $table_name = 'GroupTest_Member';

	public function getCMSFields()
	{
		$groups = DataObject::get(Group::class);
		$groupsMap = ($groups) ? $groups->map() : false;
		$fields = new FieldList(
			new HiddenField('ID', 'ID'),
			new CheckboxSetField(
				'Groups',
				'Groups',
				$groupsMap
			)
		);

		return $fields;
	}

}