Help with biology please(genetic processes)?

A research lab requires a supply of zygous spotted frogs(FF) for a cloning experiment. The lab has several frogs in its collection, but only one spotted individual and it is unknown whether this individual is zygous or heterozygous for the spotted trait, which is dominant. They need to carry out a test cross to find out whether the frog is (FF) or (H). They breed their unknown frog with a non-spotted frog. The results of the test cross is that half of the offspring are spotted and half have no spots. What is the genotype of the unknown frog?