From 79477def6b08437e4eacaf67c012ae8717bd64e3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Thu, 11 Jun 2015 23:17:16 +0200
Subject: [PATCH] tests: Write the random seed to the error port.

* guix/tests.scm (random-seed): New procedure.
  (%seed): Use it, and write the random seed to the error port.
---
 guix/tests.scm | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/guix/tests.scm b/guix/tests.scm
index 87e6cc2830..a19eda250c 100644
--- a/guix/tests.scm
+++ b/guix/tests.scm
@@ -63,8 +63,16 @@
 
       store)))
 
+(define (random-seed)
+  (or (and=> (getenv "GUIX_TESTS_RANDOM_SEED")
+             number->string)
+      (logxor (getpid) (car (gettimeofday)))))
+
 (define %seed
-  (seed->random-state (logxor (getpid) (car (gettimeofday)))))
+  (let ((seed (random-seed)))
+    (format (current-error-port) "random seed for tests: ~a~%"
+            seed)
+    (seed->random-state seed)))
 
 (define (random-text)
   "Return the hexadecimal representation of a random number."