Whenever you have to deliver to a client via a new protocol be it a new FTP, a new platform, or just a new gallery, sending a test file is always a good idea.
As someone who receives a fair amount of test files, I always both laugh and cringe when I get a test file that is clearly a test file
I have a feeling, that pot on the stove is NOT part of California vs Utah Football.
Some photographers swing the other direction, and test file using a text graphic. This is certainly more professional, but it still means that your first isn't an image at all.
If you don't have administrative access to a platform, I would recommend sending a test file and letting someone with admin access know in advance so they can confirm it uploaded and remove it.
Check It
Though test files can be silly, it would be more silly if you went to a game and only on-site realized your FTP didn't work. I am quite appreciative of anyone who prepares... and anyone who cooks!
Check In
Do you send test files? Test graphics? Or wait until you are on-site