If you want to test how user, roles, and permissions work, a simple way to do it is to make command line REST requests against the parse-server. Here's the guide.
You should be able to go into your parse dashboard and locate a user, look at their session token and then use that in queries to simulate that user's permissions.
With a session token, you can query objects in parse like this:
$ curl \
-X GET \
-H 'X-Parse-Application-Id: ABC123 \
-H "X-Parse-Session-Token: r:XXXXXX" \
-H "Content-Type: application/json" \
https://cloud.so.good/parse/classes/Product
For a complex system, you'll want to cover your cloud code to ensure that all is working as expected. A good place to start would be with parse-server's extensive test coverage, including ACL's