Well the first thing is are you sure that that is the switch to that light?
to test that turn off the breaker and the switch.
unscrew the switch from the wall, test both wires to see if there is power to either one, if the correct breaker is off you will not have any power.
Now have someone else turn the breaker on and test the 2 wires going to the switch, one is the feed in and should now have power, the other is the feed out and should not have power.
If you have power on both wires with the switch off the switch is bad.
Turn the power back off and remove one wire from the switch, turn the power on. Check the light, if it is on then that is not the switch for that light.
They may have wire it hot , but not likely, the switch may be some where else.
A single pole switch will only have 2 wires power in and power out, the switch just stops the hot leg,(black normally) the neutral (white) is spliced together in the box and does not run thru the switch.