(defun compress-test ()
  (interactive)
  (let ((sum (md5 (current-buffer) (point-min) (point-max))))
    (dolist (method '(zlib bzlib lzma))
      (message "Using %S for %d..%d" method (point-min) (point-max))
      (let ((test (progn (compress-region method (point-min) (point-max))
			 (decompress-region method (point-min) (point-max))
			 (md5 (current-buffer) (point-min) (point-max)))))
	(or (string-equal sum test) (error "%S test error" method))))))