The aim of robustness testing is to characterize the behavior of a system in the presence of erroneous or stressful input conditions. It is a well-established approach in the dependability community, which has a long tradition of testing based on fault injection. However, a recurring problem is the insufficient documentation of experiments, which may prevent their replication. Our work investigates whether UML-based documentation could be used. It proposes an extension of the UML Testing Profile that accounts for the specificities of robustness testing experiments. The extension also reuses some elements of the QoSFT profile targeting measurements. Its ability to model realistic experiments is demonstrated on a case study from dependability research.