Virtual reality or augmented reality? Maybe mixed reality? These notions are conquering the market and becoming more accessible to users. We are facing a rising demand for the development of applications that support these technologies. This is what we'll deal with. You will learn the difference and specifics of testing for each reality type – with an extra focus on MR, holograms and surfaces. I'll share my experience, speak about things to pay due attention to, deliver a few words on precautionary measures, and help you avoid real errors in the virtual world. And a little about precautions.