Dominance test. The way we test it is to take a card with a small hole about 1-2 inches square. Hold it at arms length with both eyes open and focus on something across the room. Then close one eye at a time and you will be able to see which eye was really doing the focusing. If repeatable, that is most likely the dominant eye.
Pick your favorite. Which eye do you use to look through a telescope? The eye you pick for one-eyed tasks is your dominant eye. However, eye dominance doesn't mean a hill of beans in ophthalmology., in a properly functioning normal person, both eyes work together. Each sees a slightly different picture, and the brain combines the 2 and makes 1 conscious image out of them, using the difference for depth perception.
Eye dominance. Yes. With both eyes open and your arm extended with thumb up, use your thumb to cover an object in the distance, say about 20 or so feet away. Close one eye. If the thumb remains over the object, then that is your dominant eye!