private function setThisPiwikUrl($thisUrl)
 {
     $mock = $this->getMock('stdClass', array('getValue'));
     $mock->expects($this->any())->method('getValue')->willReturnCallback(function ($key) use($thisUrl) {
         if ($key == SettingsPiwik::OPTION_PIWIK_URL) {
             return $thisUrl;
         } else {
             return "...";
         }
     });
     Option::setSingletonInstance($mock);
 }