  We present a method for the experimental measurement of nonclassicality
witnesses and demonstrate its application. Our proposal only requires the
coherent displacement of the initial state, which can be achieved by
overlapping the latter with a coherent state at a beam splitter, and subsequent
photon-number resolved detection. This setup allows a complete test of
nonclassicality of an arbitrary quantum state. The role of the quantum
efficiency as well as statistical and systematic uncertainties are discussed.
Finally, the scheme is demonstrated for a realistic example.
