Although there are solutions available, they're not suitable for the kind of testing you're probably trying to do.
One of the biggest hassles of using AFP file servers in Mac OS X is that, if you want file owner/group permissions to work, your server and all of the Mac client machines must use the same User ID and Group ID numbers for each user and group. This effectively means all your Mac clients must be bound to the same Open Directory (read: LDAP with some Apple-specific schema extensions) server as your file server is bound to, AND all the users must log into their client Macs' GUIs using their Open Directory account, not some local user account (local user accounts usually all have the same UIDs: 501, 502, etc. ).
If you were to test your server from Windows, you might find similar issues, but you'd also be struggling with Active Directory integration issues, rather than Open Directory. So you might be mostly wasting your time.