08/10: tests: Write the random seed to the error port.

[Ludovic Courtès]

civodul pushed a commit to branch master
in repository guix.

commit 79477def6b08437e4eacaf67c012ae8717bd64e3
Author: Ludovic Courtès <address@hidden>
Date:   Thu Jun 11 23:17:16 2015 +0200

    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 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/guix/tests.scm b/guix/tests.scm
index 87e6cc2..a19eda2 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."