There is a parameter OWNER in exp utility. If you mention rows=n, OWNER=xyz it will export all the objects of that particular user.

Else you can take FULL=Y as system user you get full export of the database and you can control the whatever users objects you wanted while importing to test database.

Use

from user=xyz
to user=xyz.

Make sure that user exists on the TEST database, before importing. If not just create user and default user to the right tablespace.