Test cross is a cross between individual with unknown genotype but expressing dominant phenotype and homozygous recessive individual with known genotype. It is used to determine the unknown genotype. The phenotypes of progeny will indicate the unknown genotype.
Recessive phenotypes in progenies will only be observed when they receive one recessive allele from homozygous recessive individual and other from individual tested indicating the tested individual is hybrid or heterozygous.
If all the progenies showed dominant phenotype then the individual tested will be homozygous.