A pea plant with **violet flowers** is test-crossed (× pure white). The offspring are all violet. The genotype of the parent violet plant is:

Test cross with vv (recessive): if parent were Vv, F₁ would be 1 violet : 1 white. All-violet F₁ means the parent contributed only V gametes ⇒ genotype is **VV** (homozygous dominant). This is exactly why a test cross is the standard tool to disambiguate dominant phenotypes.