Yes, test points can function like antennas. They can function like little antennas. And this is the reason why DRC(Design Rule Check) in PCB tools sometimes check for small bits of copper that go nowhere and function like antennas.
This means they can radiate as well as pick up noise. But it really depends on the frequencies involved, and the PCB construction. (I’m thinking that antenna effects would be something to worry about 50Mhz+ due to the size of the traces and the physical parameters) anything sub MHz, it probably wouldn’t be that big of a concern.
It is generally a good idea to leave test points off of analog inputs before pre-amplifiers (In sub uV designs, the analog signals are so small that a meter would interfere with the signals anyway by also picking up noise). After the pre-amp is a good place for a test point if you need to check voltages.
#PCB Design #PCB Testing