What creates this test.txt file that keeps appearing in my Home Folder?

Updated in what way? Something you are doing is creating it.
What login items do you have configured? If you login as a
different user does it appear? Where does it appear? On the
Desktop? In another folder?

Dave

never seen this but it's pretty clear that one of your programs creates it as a temp file for whatever reason and doesn't clean up after itself. I'm not sure if it's worth trying to figure out which one is doing it. you can try if you like. did you install any apps recently? delete the file and next time it's created look at the creation time and try to determine what was running at the time. if the file is created on login you can try removing your login items one at a time and see if that affects the file creation.

When does the file get created?
If you delete the file, logout then login, is a new one there?

Dave