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.

PACS numbers: 12.38.--t, 12.38.Aw