bug#24935: [PATCH] Add tests for rot13.el

[Eli Zaretskii]

> Date: Tue, 15 Nov 2016 19:43:55 +0100
> From: Simen Heggestøyl <simenheg@gmail.com>
> Cc: 24935@debbugs.gnu.org
> 
>   "ROT13 encrypt OBJECT, a buffer or string.
> Return the ROT13 encrypted string when OBJECT is a string,
> ignoring START and END.  ROT13 encrypt the region between
> positions START and END when OBJECT is a buffer; all three
> arguments are then required."

It sounds strange to describe first the use case where the arguments
are ignored.  I suggest this instead:

  ROT13 encrypt OBJECT, a buffer or string.
If OBJECT is a buffer, encrypt the region between START and END.
If OBJECT is a string, encrypt it in its entirety, ignoring START
and END, and return the encrypted string.