All "Calvinist" brethren know they have received faith, know they have faith, and know from Whom they've received it.
To state otherwise and mock saids belief and saids faith, and, to state they do not know whether or not they have faith &c is to completely misrepresent them, and is subsequently calling into question their salvation altogether.
I am not misrepresenting Calvinism at all. Google "evanescent grace". Calvin taught that God gives some a false faith that is so real that a person can truly believe themselves saved, but in reality they are not. You are just saying it another way, as false faith or real faith.
If you believe you were born a sinner that is unable to believe, then you must depend upon God to regenerate you to know you have real saving faith. But how do you know you have been regenerated? You can't know this. You can say you believe, but if you are unregenerate, this could easily be the false evanescent grace Calvin spoke of?
You don't see a difficulty there? I do. If I believed Calvinism, I would be in constant doubt about my salvation. How can I know if I was regenerated? Faith doesn't prove it, my faith could be false.
Calvin taught men to doubt so he could enslave them. They must prove by constant obedience they are saved. He learned from the Master, the RCC. It works too.