(defun test-mode (command output-file)
  "Test this code in a buffer."
  (setq old-buffer (current-buffer))
  (interactive
   (list (read-shell-command "shell command:" nil nil)
         (read-file-name "file name:")))
  (start-process-shell-command command "test-mode-process" command)
  (find-file-other-window output-file)
  (revert-buffer t t t)
  (setq buffer-read-only t)
  (other-window 1))