  We introduce a grey-box conformance testing method for networks of
interconnected Mealy Machines. This approach addresses the scenario where all
interfaces of the component under test are observable, but its inputs are under
the control of other white-box components. We prove new conditions for full
fault detection that exploit repetitions across branching executions of the
composite machine in a novel way.Finally, we provide experimental evaluation of
our approach on cascade compositions of up to a thousand states, and show that
it notably out-performs existing black-box testing techniques.
