add directory wrapper base

tests/DirectoryWrapper.php

@@ -0,0 +1,40 @@
+<?php
+/**
+ * Copyright (c) 2015 Robin Appelman <icewind@owncloud.com>
+ * This file is licensed under the Licensed under the MIT license:
+ * http://opensource.org/licenses/MIT
+ */
+
+namespace Icewind\Streams\Tests;
+
+class DirectoryWrapperDummy extends \Icewind\Streams\DirectoryWrapper {
+	public function dir_readdir() {
+		$file = parent::dir_readdir();
+		if ($file !== false) {
+			$file .= '_';
+		}
+		return $file;
+	}
+}
+
+class DirectoryWrapper extends IteratorDirectory {
+
+	/**
+	 * @param \Iterator | array $source
+	 * @return resource
+	 */
+	protected function wrapSource($source) {
+		$dir = \Icewind\Streams\IteratorDirectory::wrap($source);
+		return \Icewind\Streams\DirectoryWrapper::wrap($dir);
+	}
+
+	public function testManipulateContent() {
+		$source = \Icewind\Streams\IteratorDirectory::wrap(['asd', 'bar']);
+		$wrapped = DirectoryWrapperDummy::wrap($source);
+		$result = [];
+		while (($file = readdir($wrapped)) !== false) {
+			$result[] = $file;
+		}
+		$this->assertEquals(['asd_', 'bar_'], $result);
+	}
+}