  Precise test oracles for reactive systems such as critical control systems
and communication protocols can be modelled with deterministic finite state
machines (FSMs). Among other roles, they serve in evaluating the correctness of
systems under test. A great number of candidate precise oracles (shortly,
candidates) can be produced at the system design phase due to uncertainties,
e.g., when interpreting their requirements expressed in ambiguous natural
languages. Selecting the proper candidate becomes challenging for an expert. We
propose a test-driven approach to assist experts in this selection task. The
approach uses a non deterministic FSM to represent the candidates, includes the
partitioning of the candidates into subsets of candidates via Boolean encodings
and requires the intervention of experts to select subsets. We perform an
empirical evaluation of the applicability of the proposed approach.
