An exotic dark component, called generalized Chaplygin gas (Cg) and parameterized by an equation of state p = -A/ρ, where A and α are arbitrary constants, is one of the possible candidates for dark energy as well as for a unified scenario of dark matter and dark energy. In this paper we investigate qualitative and quantitative aspects of the angular size-redshift test in cosmological models driven by such a dark component. We discuss the prospects for constraining the Cg equation of state from measurements of the angular size at low- and high-redshift radio sources and also from a joint analysis involving angular size and supernova data. A detailed discussion about the influence of the Cg on the minimal redshift at which the angular size of an extragalactic source takes its minimal value is also presented.