use Test::NoWarnings;
use Test::Warn;

warning_like ( sub { $obj->get_member_id_by_name('smith'); }, qr /than/, 'warns when more than one name returned' );

##</code><code>##

my $had_no_warnings;
if (had_no_warnings) { 
  $had_no_warnings = 1;
}
warning_like ( sub { $obj->get_member_id_by_name('smith'); }, qr /than/, 'warns when more than one name returned' );
clear_warnings if $had_no_warnings;