My friend tested her small, about 7 lb. Chihuahua mix. He looks mostly Chi. You could make a case for him being 100%, just a really bad example, if YKWIM.
She used two different companies since she is in the animal business and got to do it for free. (as samples).
#1---Chihuahua and Husky. Not very likely since he weighs 7 lbs. But maybe he is part husky, way way way way back.
#2---Chihuahua and Corgi. This one seemed a little more likely.
As a result of these two tests, the rest of us decided to not test our dogs.
Obviously the test was accurate on the major breed, but a bit unreliable and inconsistent on the minor one.
Sadly, I do not remember what the names of the two companies she used were. It was awhile ago.