There isn't much difference really with the generic or non-generic collections. Last I checked unit tests weren't very elaborate for handling generics either.
A few pointers though:
1) Remember that you use the mangled name in the mapping files...so something like this <class name="Thing`1[System.Int32]" .../> I think this is different than Spring with the kooky syntax in their xml files.
2) You don't need to specify "generic=true" for collections in your mapping files.
3) Understand that HQL has some issues in regard to generics perhaps requiring you to work with closed generic types as workarounds. Mostly it'll be rare cases you hit this one but I have a few times. Not a showstopper tho.
4) Know this limitation too at http://forum.hibernate.org/viewtopic.php?t=970568