I'm trying to program to drive a motor (6v/12v) using uln2003, now is it ok to take the 5v power from arduino for testing purposes only? i understand the motor will not run at full efficiency but i just want to test some sketches. so is it ok? also is the internal flyback diode on uln2003 ok to use? or should i wire up a diode?
I wouldn't draw motor power from an Arduino due to the noise it will inject into the system. This can stop the Arduino from working properly. The flyback diodes should be OK though.
If you mean power from an Arduino connected to a USB port only...no. You run the risk of burning out a USB port on the computer. If you mean 5V regulated power from the Arduino with an external supply, also...no. The 5V regulator probably can't handle the current the motor will require.