  Modern-day `testing' of (perturbative) QCD is as much about pushing the
boundaries of its applicability as about the verification that QCD is the
correct theory of hadronic physics. This talk gives a brief discussion of a
small selection of topics: factorisation and jets in diffraction, power
corrections and event shapes, the apparent excess of $b$-production in a
variety of experiments, and the matching of event generators and NLO
calculations.
