Fix intermittent test failure in 80-test_cmp_http.t

output to stderr is unbuffered bypassing the normal output, which does
not happen at line boundaries and is therefore confusing the TAP parser.
This is known to cause random test failures like this one:

80-test_cmp_http.t                    (Wstat: 0 Tests: 5 Failed: 0)
  Parse errors: Tests out of sequence.  Found (6) but expected (5)
                Bad plan.  You planned 6 tests but ran 5.

Fixes #23992

Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
Reviewed-by: Saša Nedvědický <sashan@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/26363)

diff --git a/test/recipes/80-test_cmp_http.t b/test/recipes/80-test_cmp_http.t
index da4b4ffc2520739010d15d5173979be7cb05750a..7b8a5b237b37b2d733c4957cedcda178eb84bb00 100644 (file)
--- a/test/recipes/80-test_cmp_http.t
+++ b/test/recipes/80-test_cmp_http.t
@@ -293,7 +293,7 @@ sub start_server {
                           $args ? $args : ()]), display => 1);
     print "Current directory is ".getcwd()."\n";
     print "Launching $server_name server: $cmd\n";
-    my $pid = open($server_fh, "$cmd|");
+    my $pid = open($server_fh, "$cmd 2>".result_dir()."/error.txt |");
     unless ($pid) {
         print "Error launching $cmd, cannot obtain $server_name server PID";
         return 0;