yoke+circuit
some PCB manufacturers firstly examine the CAMs of the PCB,
if there is something wrong or exceeds their manufacturing ability, they warn you,
for example, if a TSOP footprint's pads to close , they warn you and they changes pads , they make them thinner.
after the manucturing, E-test (shortcircuit etc.) is applied to PCBs , with special equipments. a few automated test probes check the connectivitiy of PCB, according to CAM file.
test probes touches every pads of PCB in order to check connectivities.