--- /dev/null
+# Copyright (C) 2020 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+use Test::More;
+use PublicInbox::MIME;
+use PublicInbox::TestCommon;
+use PublicInbox::InboxWritable;
+use PublicInbox::SearchIdx;
+require_git(2.6);
+require_mods(qw(DBD::SQLite));
+
+my $addr = 'test@example.com';
+my $bad = PublicInbox::MIME->new(<<EOF);
+Message-ID: <a\@example.com>
+Message-ID: <b\@example.com>
+From: a\@example.com
+To: $addr
+Date: Fri, 02 Oct 1993 00:00:00 +0000
+Subject: bad
+
+EOF
+
+my $good = PublicInbox::MIME->new(<<EOF);
+Message-ID: <b\@example.com>
+Date: Fri, 02 Oct 1993 00:00:00 +0000
+From: b\@example.com
+To: $addr
+Subject: good
+
+EOF
+
+for my $order ([$bad, $good], [$good, $bad]) {
+ my $before;
+ my ($tmpdir, $for_destroy) = tmpdir();
+ my $ibx = PublicInbox::InboxWritable->new({
+ inboxdir => "$tmpdir/v1",
+ name => 'test-v1',
+ indexlevel => 'basic',
+ -primary_address => $addr,
+ }, my $creat_opt = {});
+ if ('setup v1 inbox') {
+ my $im = $ibx->importer(0);
+ ok($im->add($_), 'added '.$_->header('Subject')) for @$order;
+ $im->done;
+ my $s = PublicInbox::SearchIdx->new($ibx, 1);
+ $s->index_sync;
+ $before = [ $ibx->mm->minmax ];
+ $ibx->cleanup;
+ }
+ my $rdr = { 1 => \(my $out = ''), 2 => \(my $err = '') };
+ my $cmd = [ '-convert', $ibx->{inboxdir}, "$tmpdir/v2" ];
+ ok(run_script($cmd, undef, $rdr),
+ 'convert to v2');
+ $err =~ s!\AW: $tmpdir/v1 not configured[^\n]+\n!!s;
+ is($err, '', 'no errors or warnings from -convert');
+ $ibx->{version} = 2;
+ $ibx->{inboxdir} = "$tmpdir/v2";
+ is_deeply([$ibx->mm->minmax], $before,
+ 'min, max article numbers unchanged');
+}
+
+done_testing();