c# - Unit testing for Server.MapPath

Question

I've a method. which retrieve a document from hard disk. I can't test this from unit testing. It always throw an exception invalid null path or something. How to test that. I've temporarily created session for unit test. But I can't for this Server.MapPath. How to do that ?

Answer 1

You can use dependancy injection and abstraction over Server.MapPath

public interface IPathProvider
{
   string MapPath(string path);
}

And production implementation would be:

public class ServerPathProvider : IPathProvider
{
     public string MapPath(string path)
     {
          return HttpContext.Current.Server.MapPath(path);
     }
}

While testing one:

public class TestPathProvider : IPathProvider
{
    public string MapPath(string path)
    {
        return Path.Combine(@"C:project",path);
    }
}