+my $check_rethread = sub {
+ my ($desc) = @_;
+ my @warn;
+ local $SIG{__WARN__} = sub { push @warn, @_ };
+ my %config = %$ibx_config;
+ my $ibx = PublicInbox::Inbox->new(\%config);
+ my $f = $ibx->over->{dbh}->sqlite_db_filename;
+ my $over = PublicInbox::OverIdx->new($f);
+ my $dbh = $over->dbh;
+ my $non_ghost_tids = sub {
+ $dbh->selectall_arrayref(<<'');
+SELECT tid FROM over WHERE num > 0 ORDER BY tid ASC
+
+ };
+ my $before = $non_ghost_tids->();
+
+ # mess up threading:
+ my $tid = PublicInbox::OverIdx::get_counter($dbh, 'thread');
+ my $nr = $dbh->do('UPDATE over SET tid = ?', undef, $tid);
+ diag "messing up all threads with tid=$tid";
+
+ my $v2w = PublicInbox::V2Writable->new($ibx);
+ my @pr;
+ my $pr = sub { push @pr, @_ };
+ $v2w->index_sync({reindex => 1, rethread => 1, -progress => $pr});
+ # diag "@pr"; # nobody cares
+ is_deeply(\@warn, [], 'no warnings on reindex + rethread');
+
+ my @n = $dbh->selectrow_array(<<EOS, undef, $tid);
+SELECT COUNT(*) FROM over WHERE tid <= ?
+EOS
+ is_deeply(\@n, [ 0 ], 'rethread dropped old threadids');
+ my $after = $non_ghost_tids->();
+ ok($after->[0]->[0] > $before->[-1]->[0],
+ 'all tids greater than before');
+ is(scalar @$after, scalar @$before, 'thread count unchanged');
+};
+
+$check_rethread->('no-monster');
+