Each switch should be grounded with bare copper wires coming from the green screws on the switches, to a bare copper wire screwed onto one of the wire clamp screws of the metal box, to the bare copper wires of all incoming cables.
All of these wires should be interconnected in a sound and professionally clean way.
To test that everything is properly grounded you can use a standard multimeter tool to test resistance or continuity between a grounded source and the neutral wire feeding the box.
You can set your voltimeter to continuity or to a low resistance setting as shown above. Touching one end to neutral and another to ground should show near zero resistance on the display because the neutral and ground bars are connected at the breaker box. Near zero resistance means that they are continuous.
A high resistance number or a display of 1 essentially means that there is infinite resistance between ground and neutral, and that means that the receptacle or switch you are testing is not grounded.
Put one end on the green screw of one of the switches and the other on the neutral to test each switch.
Next place one end on the metal box itself and the other to the neutral wire to verify the box is grounded.
Next test all the other ground wires from all other cables to verify that they are all grounded as well.
You will be able to perform this test safely with the breaker(s) shut off as you won't need a live power source to test continuity.