nntp: fix LIST OVERVIEW.FMT ordering and format

RFC3977 8.4.2 mandates the order of non-standard headers
to be after the first seven standard headers/metadata;
so "Xref:" must appear after "Lines:"|":lines".

Additionally, non-required header names must be followed
by ":full".

Cc: Jonathan Corbet <corbet@lwn.net>
Reported-by: Urs Janßen
	<E1hmKBw-0008Bq-8t@akw>

1 files changed, 6 insertions, 0 deletions

diff --git a/t/nntpd.t b/t/nntpd.t
index e264fa6b..bebecc69 100644
--- a/t/nntpd.t
+++ b/t/nntpd.t
@@ -101,6 +101,12 @@ EOF
         is_deeply([$n->group($group)], [ qw(0 1 1), $group ], 'GROUP works');
         is_deeply($n->listgroup($group), [1], 'listgroup OK');
 
+        {
+                my $expect = [ qw(Subject: From: Date: Message-ID:
+                                References: Bytes: Lines: Xref:full) ];
+                is_deeply($n->overview_fmt, $expect,
+                        'RFC3977 8.4.2 compliant LIST OVERVIEW.FMT');
+        }
         SKIP: {
                 $n->can('starttls') or
                         skip('Net::NNTP too old to support STARTTLS', 2);