I think you tested the presence of voltage to the pump but not the pump itself.

I once tried to apply a test light to the neg coil terminal and it stopped the engine. I concluded that the relatively low resistance of the bulb (it was a tail light bulb) did not allow the voltage to rise to 12V in between the \ negative going driving pulses from the power stage. Your test bulb may be smaller wattage (higher resistance) and it is allowing the engine to continue running. I think your result is normal.
To check for presence of pulses from the power stage why not just watch the tach itself. It will plunge to zero faster than the actual engine rpms if spark pulses stop.