Use sort and dir functions together with wildcard:
DIRECTORY = $(sort $(dir $(wildcard ../Test/*/)))
From GNU make manual:
$(dir names…)
Extracts the directory-part of each file name in names. The directory-part of the file name is everything up through (and including) the last slash in it. If the file name contains no slash, the directory part is the string ‘./’.$(sort list)
Sorts the words of list in lexical order, removing duplicate words. The output is a list of words separated by single spaces.
Also look at the second and the third method in this article: Automatically Creating a List of Directories