Ex. 1) Joe Bloggs asks me if I'll Force test him. I agree. He boards my ship, I test him, he's FS, I reveal the answer to him, etc...
Ex. 2)I encounter Fred Sggolb in the street one day. He's not moving and I decide to Force test him just because I can. He's FS, but I don't bother to tell him because I don't know what faction he's with, if he's an annoying noob, etc. But I might send him a DM and chat with him to find out, and offer him another Force test later if I like him.
Ex. 3) Mikel von Bianchi, from the GE, is walking around on Gand. I'm not hostile with the GE, but not necessarily too friendly either, so I'm a little wary and suspicious. I Force test him to find out what level of "problem" he might be if he chooses to cause trouble. I find him to be FS, and I plan accordingly.
Example 1 is the only situation where the person is going to know they've been tested, let alone if I want them to know the result. I suspect it's also the only scenario you were considering.
____________"May the Grace of Ara go with you, and His Vengeance be wrought upon your enemies."
Only fools and children dream of heroes.