silverstripe-testsession/code/TestSesssionRequestFilter.php

<?php
/**
 * Sets state previously initialized through {@link TestSessionController}.
 */
class TestSessionRequestFilter {
	
	public function preRequest($req, $session, $model) {
		if(!$session->inst_get('testsession.started')) return;

		// Date and time
		if($datetime = $session->inst_get('testsession.datetime')) {
			SS_Datetime::set_mock_now($datetime);
		}

		// Register mailer
		if($mailer = $session->inst_get('testsession.mailer')) {
			Email::set_mailer(new $mailer());
			Config::inst()->update("Email","send_all_emails_to", null);
		}

		// Allows inclusion of a PHP file, usually with procedural commands
		// to set up required test state. The file can be generated
		// through {@link TestSessionStubCodeWriter}, and the session state
		// set through {@link TestSessionController->set()} and the
		// 'testsessio.stubfile' state parameter.
		$file = $session->inst_get('testsession.stubfile');
		if(!Director::isLive() && $file && file_exists($file)) {
			// Connect to the database so the included code can interact with it
			global $databaseConfig;
			if ($databaseConfig) DB::connect($databaseConfig);
			include_once($file);
		}
	}

	public function postRequest() {
	}
}