Computing environments, including virtual machines and containers, are essential components of modern software engineering infrastructure. Despite emerging tools that support the creation and configuration of computing environments, they are limited in testing and validating the construction of these environments. Furthermore, professionals and students new to these concepts, lack feedback on their construction efforts. In this paper, we argue that the design of environment testing tools should fundamentally support asserting essential properties, such as reachability and availability, in order to maximize usability and utility. We present opunit, an environment testing tool that supports assertion of these properties. We describe properties students failed to check when testing computing environments, which guided the design of opunit. Finally, we share our early experiences with using opunit in the classroom to support education and training in configuration of computing environments.