When does "cart/updated" event fires ? Does it fire when user add product into cart ?

Hi,

I have tried to use cart/updated event but.. it never fires. Not in console testing , not in real app, as I tested applying changes to live as well.

Tapcart.registerEventHandler("cart/updated", function (eventData) {

console.log("VISITOR ADDED PRODUCT"); // this never fires.

});

Do you have a working test sample for it ?