marionette: Factorize 'wait-for-file'.

* gnu/build/marionette.scm (wait-for-file): New procedure.
* gnu/tests/base.scm (run-mcron-test)[test](wait-for-file): Remove.
Pass second argument in 'wait-for-file' calls.
* gnu/tests/ssh.scm (run-ssh-test)[test](wait-for-file): Remove.
Pass second argument in 'wait-for-file' calls.
* gnu/tests/messaging.scm (run-xmpp-test)[test](guest-wait-for-file):
Remove.
Use 'wait-for-file' instead, with second argument.

1 files changed, 16 insertions, 1 deletions

diff --git a/gnu/build/marionette.scm b/gnu/build/marionette.scm
index 506d6da420..424f2b6713 100644
--- a/gnu/build/marionette.scm
+++ b/gnu/build/marionette.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2016 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2016, 2017 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -25,6 +25,7 @@
   #:export (marionette?
             make-marionette
             marionette-eval
+            wait-for-file
             marionette-control
             marionette-screen-text
             wait-for-screen-text
@@ -164,6 +165,20 @@ QEMU monitor and to the guest's backdoor REPL."
      (newline repl)
      (read repl))))
 
+(define* (wait-for-file file marionette #:key (timeout 10))
+  "Wait until FILE exists in MARIONETTE; 'read' its content and return it.  If
+FILE has not shown up after TIMEOUT seconds, raise an error."
+  (marionette-eval
+   `(let loop ((i ,timeout))
+      (cond ((file-exists? ,file)
+             (call-with-input-file ,file read))
+            ((> i 0)
+             (sleep 1)
+             (loop (- i 1)))
+            (else
+             (error "file didn't show up" ,file))))
+   marionette))
+
 (define (marionette-control command marionette)
   "Run COMMAND in the QEMU monitor of MARIONETTE.  COMMAND is a string such as
 \"sendkey ctrl-alt-f1\" or \"screendump foo.ppm\" (info \"(qemu-doc)