In this paper, an over-the-air test strategy for evaluating cognitive radio nodes is presented. This technique allows to emulate the activities of primary and secondary users with respect to received power spectral densities, and the spatial structures of their radio channels. This enables an experimental evaluation of cognitive devices with directional and spectral sensitivity. This type of testing is more realistic than conducted tests, as it includes all antenna effects involved in the perception of the radio environment. A multi-level test procedure is proposed, which implements different levels of complexity in terms of the operation of the device-under-test, the synthetic radio environment, and the required complexity of the test setup. A proof of principle based on an experiment is presented.