I hope you fail the test, too. :)
Here's a decent explanation of it, complete with pics - https://www.medicalnewstoday.com/articles/320496.php
Do you have anyone to drive you to and from? You might want to make plans for that. The article mentions morphine. If you get that, you certainly won't be able to drive.
When is your scan? Let us know what happens, and good luck! I hope you fail with flying colors. :)