Oracle 11.2 restore DB to a specific point
From the very first lines in the Oracle Documentation about Flashback Database feature ( https://docs.oracle.com/cd/E11882_01/backup.112/e10643/rcmsynta023.htm#RCMRF194 ):


  This command works by undoing changes made by Oracle Database to the data files that exist when you run the command.


Flashback its mean to undo logical changes in the database. A Backup its a cloned copy of your database in a point in time. So, if you want to reproduce the exactly same environment for any subsequent tests, involving DB changes, you should go for a RMAN backup/restore technique.

Also, for the single instance DB, If it's going to be just a Test environment, you could avoid the creation of Archives and Flashback logs for saving lots of space, and create/restore from cold backups.

Scripting to recreate the DB + dp exp/imp can be another option, but its a waste of time having RMAN.