They didn't even know I was coming, so they first hit me with a quick test for a testing engineer position. I told them that's not qhy I was there so the manager qho was interviewing me started improvising.
It was the most relevant interview I had.
We talked about concept, limit cases, basic programming knowldge and after passing that one I had to write a simple C++ program to proove my style and design a more complex one, just UML.
They said theyr HR was in leave, so they coudn't make a offer riht away, and I was in a hurry to find a job.
But this on-spot interview laid an impression on me.