I am using PowerShell version 5.0.10018.0 for the examples. This version of PowerShell ships with the WMF February 2015 Preview package that you can download here.
I was asked if there are any resources on testing class based DSC resources. And to be honest I am not sure. We shortly discussed the possibilities on the PS MVP mailing list, but I am still not sure what are the possibilities. So why not discover them while learning something more about the topic.
Luckily there are quite a few great resources on how to actually create a class based DSC resource, and what you need to do that. Some of them are:
Creating a Class based DSC Resource using PowerShell
Class-defined DSC resources in Windows Management Framework 5.0 Preview
Writing a custom DSC resource with PowerShell classes