[PATCH 2/2] test: use emacsclient(1) for Emacs tests
Dmitry Kurochkin
dmitry.kurochkin at gmail.com
Mon Jun 27 20:59:48 PDT 2011
On Mon, 27 Jun 2011 23:49:37 -0400, Austin Clements <amdragon at MIT.EDU> wrote:
> Quoth Dmitry Kurochkin on Jun 28 at 5:03 am:
> > > > The only way I know to
> > > > reliably kill a child process is to open a pipe to it and have it exit
> > > > on its own when it reads EOF. Unfortunately, I couldn't find a way to
> > > > do this with an emacs daemon (it appears daemon mode aggressively
> > > > cleans up things like pipes), but here's a different approach:
> > > >
> > > > coproc emacs --batch --eval "(while t (eval (read)))"
> > > > EMACSFD=${COPROC[1]}
> > > > trap "echo '(kill-emacs)' >&$EMACSFD" EXIT
> > > >
> > > > echo '(message "Hi")' >&$EMACSFD
> > > > # ...
> > > >
> > > > This is, basically, a poor man's emacs server, but the coprocess pipe
> > > > binds it tightly to the shell. If the shell exits for *any* reason,
> > > > the pipe will be closed by the kernel, emacs will read an EOF, and
> > > > exit.
> > >
> > > I like this idea.
> > >
> > > > The trap is there just to cleanly shut down in case of a normal
> > > > exit [1].
> > >
> > > For normal exit we should just put this into test_done. Otherwise it is
> > > not a normal exit and we do not care about Emacs error message. No?
> > >
> > > > This also has the advantage that read-from-minibuffer still
> > > > works:
> > > >
> > > > echo '(message (read-from-minibuffer ""))' >&$EMACSFD
> > > > echo 'Test' >&$EMACSFD
> > > >
> > > > Thoughts?
> > > >
> > >
> > > I like it and I will implement it. Thanks for the idea.
> > >
> >
> > While implementing the idea, I stumbled upon a problem: we need to know
> > when Emacs finished what we echoed or failed with an error. At the
> > moment tests fail because they check for OUTPUT before Emacs creates it.
> >
> > We can tell Emacs to print some special marker and wait for it. But
> > there may be exceptions and errors which may make it difficult. I did
> > not found a good solution yet. Would love to hear your thoughts :)
>
> Oof, yes, of course. How about making the one-line poor man's emacs
> server slightly less poor? Use a FIFO to communicate completion.
> Something like,
>
> EMACSDONE=$TEST_DIRECTORY/emacsdone
> mkfifo $EMACSDONE
> coproc emacs --batch --eval '(while t (eval (read)) (write-region "\n" nil "'$EMACSDONE'" t 0))'
> EMACSFD=${COPROC[1]}
>
> test_emacs() {
> echo "$1" >&$EMACSFD
> read <$EMACSDONE
> }
>
> test_emacs '(sleep-for 2)'
> test_emacs '(message "Hi")'
>
> echo '(kill-emacs)' >&$EMACSFD
I am sure that would work, but I do not like the complexity. How about
getting back to standard emacsclient and running a watchdog in the
emacs? Like:
(defun orphan-watchdog (pid)
"Periodically check that the process with id PID is still
running, quit if it terminated."
(if (not (process-attributes pid))
(kill-emacs)
(run-at-time "1 min" nil orphan-watchdog pid)))
This function (or my other changes) do not work (by yet unknown reason
:)), but you get the idea.
Regards,
Dmitry
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