t/spawn: Find invalid PID to try to join its process group

[public-inbox.git] / t / spawn.t

diff --git a/t/spawn.t b/t/spawn.t
index 6168c1f6171c83919efefa91d7194a5a8b069c1b..5fc99a2a101c8c2c83466e515a84bba471b9546e 100644 (file)
--- a/t/spawn.t
+++ b/t/spawn.t
@@ -24,7 +24,18 @@ SKIP: {
        is(waitpid($pid, 0), $pid, 'waitpid succeeds on spawned process');
        is($?, 0, 'true exited successfully');
        pipe(my ($r, $w)) or BAIL_OUT;
-       $pid = eval { spawn(['true'], undef, { pgid => 1, 2 => $w }) };
+
+       # Find invalid PID to try to join its process group.
+       my $wrong_pgid = 1;
+       for (my $i=0x7fffffff; $i >= 2; $i--) {
+               if (kill(0, $i) == 0) {
+                       $wrong_pgid = $i;
+                       last;
+               }
+       }
+
+       # Test spawn behavior when it can't join the requested process group.
+       $pid = eval { spawn(['true'], undef, { pgid => $wrong_pgid, 2 => $w }) };
        close $w;
        my $err = do { local $/; <$r> };
        # diag "$err ($@)";