I am trying to write Unit Test in C# for static methods.

I am learning unit test for c# web application. I am stuck in above mention scenario. I am not if I am doing it in correct way. I have FakePath class for unit test. How do I write unit test for static method,Abc.log(), in MSTest?

public class Abc{
    public static void log(string msg)
    {   
    string path=getPath(new ServerPath());
    //Read on Write on path;
}

public static string getPath(IServerPath path)
{
return path.MapPath("file.txt");
}

}

interface IServerPath(){
string MapPath(string file);
}

class ServerPath:IServerPath
{
string MapPath(string file){
return HttpContext.Current.Server.MapPath(file);
}
}
class FakeServerPath:IServerPath
    {
    string MapPath(string file){
    return @"C:\"+file;
    }