Added unit test for the test() method

This is to make sure that method isn't broken

lib/private/files/storage/wrapper/wrapper.php

@@ -424,4 +424,12 @@ class Wrapper implements \OC\Files\Storage\Storage {
 	public function getETag($path) {
 		return $this->storage->getETag($path);
 	}
+
+	/**
+	 * Returns true
+	 * @return true
+	 */
+	public function test() {
+		return $this->storage->test();
+	}
 }

tests/lib/files/storage/storage.php

@@ -42,6 +42,13 @@ abstract class Storage extends \PHPUnit_Framework_TestCase {
 		$this->assertTrue($this->instance->isUpdatable('/'), 'Root folder is not writable');
 	}
 
+	/**
+	 * Check that the test() function works
+	 */
+	public function testTestFunction() {
+		$this->assertTrue($this->instance->test());
+	}
+
 	/**
 	 * @dataProvider directoryProvider
 	 */