+$date_string = output_pref( $dt, 'iso', '12hr' );
+cmp_ok $date_string, 'eq', '2011-06-16 12:00 PM', 'iso output 12hr';
+
+# "notime" doesn't actually mean anything in this context, but we
+# can't pass undef or output_pref will try to access the database
+$date_string = output_pref( $dt, 'iso', 'notime', 1 );
+cmp_ok $date_string, 'eq', '2011-06-16', 'iso output (date only)';
+
+$date_string = output_pref( $dt, 'us', '24hr' );