public function testPrefixIfNeeded()
 {
     $dm = new Downloader();
     $cm1 = new ConfigManager(array("ZipBackupFolder" => "bla"), $this->dm);
     $cm1->prefixIfNeeded("foo");
     $this->assertEquals($cm1->config["ZipBackupFolder"], "foo/bla");
     $cm2 = new ConfigManager(array("ZipBackupFolder" => "/bla"), $this->dm);
     $cm2->prefixIfNeeded("foo");
     $this->assertEquals($cm2->config["ZipBackupFolder"], "/bla");
 }