patchtester/administrator/components/com_patchtester/patchtester.php

<?php
/**
 * Patch testing component for the Joomla! CMS
 *
 * @copyright  Copyright (C) 2011 - 2012 Ian MacLennan, Copyright (C) 2013 - 2016 Open Source Matters, Inc. All rights reserved.
 * @license    GNU General Public License version 2 or later
 */

defined('_JEXEC') or die;

// Access check.
if (!JFactory::getUser()->authorise('core.manage', 'com_patchtester'))
{
	throw new RuntimeException(JText::_('JERROR_ALERTNOAUTHOR'), 403);
}

// Application reference
$app = JFactory::getApplication();

// Register the component namespace to the autoloader
JLoader::registerNamespace('PatchTester', __DIR__);

// Build the controller class name based on task
$task = $app->input->getCmd('task', 'display');

// If $task is an empty string, apply our default since JInput might not
if ($task === '')
{
	$task = 'display';
}

$class = '\\PatchTester\\Controller\\' . ucfirst(strtolower($task)) . 'Controller';

if (!class_exists($class))
{
	throw new InvalidArgumentException(JText::sprintf('JLIB_APPLICATION_ERROR_INVALID_CONTROLLER_CLASS', $class), 404);
}

// Instantiate and execute the controller
/** @var \PatchTester\Controller\AbstractController $controller */
$controller = new $class($app->input, $app);
$controller->execute();