Test for power. - used a small pocket type 3 light tester looks for 110, 240, 600 and I checked at the wires not the plug
I did not use a volt meter
I only tested hot to neutral
I do have a volt meter and I can check neutral to ground (not done yet)
house is less than 10 years old. Slab
there are GFCI's in bathrooms and kitchen near water. the one in question out back is not.