C# - How can i wrap a static class

Question

I want to make util classes for System.Io (such as File, Directory etc).

Since inheritance cannot be done for static classes i want to know how would be a proper way to wrap lets say System.Io.File.

Answer 1

I would create three types:

• An interface containing all the methods you want to be able to test etc, eg

   public interface IFileSystem { Stream OpenWrite(string filename); TextReader OpenText(string filename); // etc } 

• An implementation which delegates to the system implementation:

   public class FrameworkFileSystem : IFileSystem { public Stream OpenWrite(string filename) { return File.OpenWrite(filename); } // etc } 

• A fake implementation for testing:

   public class FakeFileSystem : IFileSystem { // Probably all kinds of things to allow in-memory files // to be created etc } 

You may well not want to put everything from File in there though - as many of the operations can be composed from the "core" ones. Of course, that would mean reimplementing the operations yourself, which may be undesirable...