Add directory filter

tests/DirectoryFilter.php

@@ -0,0 +1,44 @@
+<?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 DirectoryFilter extends \PHPUnit_Framework_TestCase {
+	public function testFilterAcceptAll() {
+		$this->filter(['a', 'b', 'c'],
+			function () {
+				return true;
+			},
+			['a', 'b', 'c']);
+	}
+
+	public function testFilterRejectAll() {
+		$this->filter(['a', 'b', 'c'],
+			function () {
+				return false;
+			},
+			[]);
+	}
+
+	public function testFilterRejectLong() {
+		$this->filter(['a', 'bb', 'c'],
+			function ($file) {
+				return strlen($file) < 2;
+			},
+			['a', 'c']);
+	}
+
+	private function filter(array $files, callable $filter, array $expected) {
+		$source = \Icewind\Streams\IteratorDirectory::wrap($files);
+		$filtered = \Icewind\Streams\DirectoryFilter::wrap($source, $filter);
+		$result = [];
+		while (($file = readdir($filtered)) !== false) {
+			$result[] = $file;
+		}
+		$this->assertEquals($expected, $result);
+	}
+}