I am trying to get the path to a folder in my website root and save it to a class property when my controller constructor is called:
public TestController:Contro
Try going through the ControllerContext. Forgive my syntax, but it should something like this:
base.[Controller?]Context.HttpContext.Server.MapPath();
If Server is still null in that situation, are you running outside of a web request (ie. in a test)?