[ticket/security-171] Modify tests for new file_downloader class

SECURITY-171

tests/mock/file_downloader.php

@@ -0,0 +1,27 @@
+<?php
+/**
+*
+* This file is part of the phpBB Forum Software package.
+*
+* @copyright (c) phpBB Limited <https://www.phpbb.com>
+* @license GNU General Public License, version 2 (GPL-2.0)
+*
+* For full copyright and license information, please see
+* the docs/CREDITS.txt file.
+*
+*/
+
+class phpbb_mock_file_downloader extends \phpbb\file_downloader
+{
+	public $data;
+
+	public function set($data)
+	{
+		$this->data = $data;
+	}
+
+	public function get($host, $directory, $filename, $port = 80, $timeout = 6)
+	{
+		return $this->data;
+	}
+}