+# upgrade existing basic to medium
+# note: changing indexlevels is not yet supported in v2,
+# and may not be without more effort
+$ibx_config->{indexlevel} = 'medium';
+$ibx = PublicInbox::Inbox->new($ibx_config);
+$rw = PublicInbox::SearchIdx->new($ibx, 1);
+# no removals
+{
+ my @warn;
+ local $SIG{__WARN__} = sub { push @warn, @_ };
+ eval { $rw->index_sync };
+ is($@, '', 'no error from indexing');
+ is_deeply(\@warn, [], 'no warnings');
+ my $mset = $ibx->search->reopen->query('hello world', {mset=>1});
+ isnt(0, $mset->size, 'search OK after basic -> medium');
+}