  We analyse nonclassical resources in interference phenomena using generalized
noncontextuality inequalities and basis-independent coherence witnesses. We use
recently proposed inequalities that witness both resources within the same
framework. We also propose, in view of previous contextual advantage results, a
systematic way of applying these tools to characterize advantage provided by
coherence and contextuality in quantum information protocols. We instantiate
this methodology for the task of quantum interrogation, famously introduced by
the paradigmatic bomb-testing interferometric experiment, showing contextual
quantum advantage for such a task.
