diff --git a/tests/lib/helper.php b/tests/lib/helper.php
new file mode 100644
index 0000000000..b12f8d929b
--- /dev/null
+++ b/tests/lib/helper.php
@@ -0,0 +1,144 @@
+<?php
+/**
+ * Copyright (c) 2012 Lukas Reschke <lukas@statuscode.ch>
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
+ */
+
+class Test_Helper extends UnitTestCase {
+	function testMakeURLAbsolute() {
+		$result = OC_Helper::makeURLAbsolute("/index.php?someParameter=value");
+		$expected = 'http://localhost/index.php?someParameter=value';
+		$this->assertEquals($result, $expected);
+	}
+
+	function testHumanFileSize() {
+		$result = OC_Helper::humanFileSize(0);
+		$expected = '0 B';
+		$this->assertEquals($result, $expected);
+
+		$result = OC_Helper::humanFileSize(1024);
+		$expected = '1 kB';
+		$this->assertEquals($result, $expected);
+
+		$result = OC_Helper::humanFileSize(10000000);
+		$expected = '9.5 MB';
+		$this->assertEquals($result, $expected);
+
+		$result = OC_Helper::humanFileSize(500000000000);
+		$expected = '465.7 GB';
+		$this->assertEquals($result, $expected);
+	}
+
+	function testComputerFileSize() {
+		$result = OC_Helper::computerFileSize("0 B");
+		$expected = '0.0';
+		$this->assertEquals($result, $expected);
+
+		$result = OC_Helper::computerFileSize("1 kB");
+		$expected = '1024.0';
+		$this->assertEquals($result, $expected);
+
+		$result = OC_Helper::computerFileSize("9.5 MB");
+		$expected = '9961472.0';
+		$this->assertEquals($result, $expected);
+
+		$result = OC_Helper::computerFileSize("465.7 GB");
+		$expected = '500041567436.8';
+		$this->assertEquals($result, $expected);
+	}
+
+	function testGetMimeType() {
+		$result = OC_Helper::getMimeType("./data/");
+		$expected = 'httpd/unix-directory';
+		$this->assertEquals($result, $expected);
+
+		$result = OC_Helper::getMimeType("./data/data.tar.gz");
+		$expected = 'application/x-gzip';
+		$this->assertEquals($result, $expected);
+
+		$result = OC_Helper::getMimeType("./data/data.zip");
+		$expected = 'application/zip';
+		$this->assertEquals($result, $expected);
+
+		$result = OC_Helper::getMimeType("./data/logo-wide.svg");
+		$expected = 'image/svg+xml';
+		$this->assertEquals($result, $expected);
+
+		$result = OC_Helper::getMimeType("./data/logo-wide.png");
+		$expected = 'image/png';
+		$this->assertEquals($result, $expected);
+	}
+
+	function testGetStringMimeType() {
+		$result = OC_Helper::getStringMimeType("/data/data.tar.gz");
+		$expected = 'text/plain; charset=us-ascii';
+		$this->assertEquals($result, $expected);
+	}
+
+	function testIssubdirectory() {
+		$result = OC_Helper::issubdirectory("./data/", "/anotherDirectory/");
+		$this->assertFalse($result);
+
+		$result = OC_Helper::issubdirectory("./data/", "./data/");
+		$this->assertTrue($result);
+
+		mkdir("data/TestSubdirectory", 0777);
+		$result = OC_Helper::issubdirectory("data/TestSubdirectory/", "data");
+		rmdir("data/TestSubdirectory");
+		$this->assertTrue($result);
+	}
+
+	function testMb_array_change_key_case() {
+		$arrayStart = array(
+			"Foo" => "bar",
+			"Bar" => "foo",
+			);
+		$arrayResult = array(
+			"foo" => "bar",
+			"bar" => "foo",
+			);
+		$result = OC_Helper::mb_array_change_key_case($arrayStart);
+		$expected = $arrayResult;
+		$this->assertEquals($result, $expected);
+
+		$arrayStart = array(
+			"foo" => "bar",
+			"bar" => "foo",
+			);
+		$arrayResult = array(
+			"FOO" => "bar",
+			"BAR" => "foo",
+			);
+		$result = OC_Helper::mb_array_change_key_case($arrayStart, MB_CASE_UPPER);
+		$expected = $arrayResult;
+		$this->assertEquals($result, $expected);	
+	}
+
+	function testMb_substr_replace() {
+		$result = OC_Helper::mb_substr_replace("This  is a teststring", "string", 5);
+		$expected = "This string is a teststring";
+		$this->assertEquals($result, $expected);
+	}
+
+	function testMb_str_replace() {
+		$result = OC_Helper::mb_str_replace("teststring", "string", "This is a teststring");
+		$expected = "This is a string";
+		$this->assertEquals($result, $expected);
+	}
+
+	function testRecursiveArraySearch() {
+		$haystack = array(
+			"Foo" => "own",
+			"Bar" => "Cloud",
+			);
+
+		$result = OC_Helper::recursiveArraySearch($haystack, "own");
+		$expected = "Foo";
+		$this->assertEquals($result, $expected);
+
+		$result = OC_Helper::recursiveArraySearch($haystack, "NotFound");
+		$this->assertFalse($result);
+	}
+}
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