Added some testcases for an empty list and empty associative arrays

[hannesg]

Hi

the title says all. The RFC mentions only one example and is not very verbose about the handling of empty lists and assocs.

Thank you
Hannes

[andreineculau]

Are you sure about the expansion of the {?empty_list} into ?empty_list= and similarly for the associative array?
As per the RFC definition, empty_list and empty_assoc variables are undefined, so then why would they be expanded, rather than omitted?

   A variable defined as a list value is considered undefined if the
   list contains zero members.  A variable defined as an associative
   array of (name, value) pairs is considered undefined if the array
   contains zero members or if all member names in the array are
   associated with undefined values.