Please add Preprocessing steps Test function for all items. For items that cannot collect data at the request of the user, you can simply leave the field for entering data manually.

For now test button for "Zabbix agent (active)" or "Zabbix trapper" items type are not available.

But usually this Test possibility used not for actual data gathering but for preprocessing steps testing. Since Zabbix support JavaScript and other complicated preprocessing method that is super useful

Also, in fact we can still test items without actually data fetching by unchecking "Get value from host" checkbox: