Measuring load resistance/inductance in an electric motor
You seem to be asking about the resistance that a DC motor represents as the load on an electronic speed controller. That resistance is very low and is not operating voltage divided by load current. Armature Resistance = (Operating Voltage - Back EMF) / Load Current. The back EMF is proportional to motor speed. The armature inductance could be determined somewhat as you suggest, but with a low voltage applied and the motor shaft clamped down to prevent is from turning, commonly known as "locked-rotor" or "blocked-rotor."

I believe the rotor resistance is also determined using a locked-rotor test. In both cases, there may be some variation with different armature positions due to the way in which the brushes transition between commutator segments. It may also be desirable to determine the brush resistance separately.