Even if usability is becoming a hot topic both in industry and academic research, very little work has been done on the modeling and formalizing of empirical studies, in particular on usability testing processes. Process modeling is fundamental, not only for process maturity, standardization, and customization to different types of empirical studies, but also for the automation and integration of usability testing in the mainstream of software development lifecycle. Moreover, there is a big gap between usability testing practices and usability tools. Most of current tools used in usability testing cover only a few steps and activities of the testing process. We lack integrated toolsets that can support the whole usability testing process.  Within this context, we reviewed the existing usability testing process models while highlighting their limitations. We then proposed a ten-step, well-defined and structured process that combines all strengths and overcomes the drawbacks of current processes. We also demonstrated how such a well-defined process can be embedded into a web-based wizard, WizUse, to assist usability professionals managing, customizing, and conducting usability tests. To validate our approach, we also conducted a series of tests to demonstrate that the proposed process model and WizUse are a suitable approach to bridge the gap between current usability practices and tools