For most situations, we can work with you on how to test implementation of new functionality, including a new student data import file, without needing a test site.  We do not typically allow access to a test site once your site is live.

If you wish to test your student data import file, you may temporarily unmap your headers as follows:

1. Go to Site > Settings > User Imports
2. Under User Import Settings, make note of the Email Header and UID Header current settings.  You should consider taking a screenshot to document these settings as you will need to set them back EXACTLY as they are once you are done testing.

User Import screen showing header settings

3. Click into Email Header, and select the "blank" option
4. Click into UID Header, and select the "blank" option
5. Click Update Settings

You have now unmapped the UID and Email headers, both of which the system needs to map import data into the system.  This way, you can see the results of your import file without affecting current import data in your system.
Warning: Once your testing is complete, it is very important that you remap the Email Header and the UID Header back to how they were or else your import data will not map into the system!