add option to check if shim is in use - How to check if the system is using shim or not?

[adrelanos]

I've created an ISO with shim which really wasn't simple at all. Now I am testing it with QEMU.

Since shim as far as I know and please correct me if I am wrong doesn't produce any visual output, no log messages, hands over control to grub and is then "gone" it seems totally invisible.

How can I test if shim has booted first or if grub was booted?

Why do I want to know that? For the purpose of developing a QEMU based unit test that checks if the boot sequence (shim first) is correct.