Define and design a test cross.

(N/A) test cross is a genetic cross between an individual with an unknown genotype (showing a dominant phenotype) and a homozygous recessive parent. It is used to determine whether the individual is homozygous or heterozygous for a specific trait.
If the progeny produced by a test cross shows $50 \%$ dominant trait and $50 \%$ recessive trait (a $1:1$ ratio),then the unknown individual is heterozygous $(Rr)$.
On the other hand,if all the progeny produced show the dominant trait,then the unknown individual is homozygous dominant $(RR)$.