code: protected function checkServerConfiguration()
      {
          $pico = $this->picoAuth->getPico();
  
          // Pico config.yml file
          $configDir = $pico->getBaseUrl() . basename($pico->getConfigDir());
          $configFile = $configDir . "/config.yml";
  
          // index.md file
          $contentDir = $pico->getBaseUrl() . basename($pico->getConfig('content_dir'));
          $indexFile = $contentDir . "/index" . $pico->getConfig('content_ext');
  
          $urls = array(
              'dir_listing' => $configDir,
              'config_file' => $configFile,
              'content_file' => $indexFile
          );
  
          $this->httpsTest();
          $this->webRootDirsTest();
          $this->picoAuth->addOutput("installer_urltest", $urls);
      }
docs: Gets absolute Urls for pre-installation test
  
  In order to perform checks that the server configuration does not
  allow public access to Pico configuration or content directory,
  the tested Urls are passed to Javascript, where response
  tests are performed using AJAX calls.
  
  The method assumes default locations of the config and content
  directories, as specified in the Pico's index.php file.