Handle changes in FileProviders.

Author: Tratcher

test/Microsoft.AspNet.StaticFiles.Tests/StaticFileContextTest.cs

@@ -66,7 +66,7 @@ public void AddFile(string path, IFileInfo fileInfo)
 
             public IDirectoryContents GetDirectoryContents(string subpath)
             {
-                return new NotFoundDirectoryContents();
+                throw new NotImplementedException();
             }
 
             public IFileInfo GetFileInfo(string subpath)
@@ -77,13 +77,69 @@ public IFileInfo GetFileInfo(string subpath)
                     return result;
                 }
 
-                return new NotFoundFileInfo(subpath);
+                return new NotFoundFileInfo();
             }
 
             public IExpirationTrigger Watch(string filter)
             {
                 throw new NotSupportedException();
             }
+
+            private class NotFoundFileInfo : IFileInfo
+            {
+                public bool Exists
+                {
+                    get
+                    {
+                        return false;
+                    }
+                }
+
+                public bool IsDirectory
+                {
+                    get
+                    {
+                        throw new NotImplementedException();
+                    }
+                }
+
+                public DateTimeOffset LastModified
+                {
+                    get
+                    {
+                        throw new NotImplementedException();
+                    }
+                }
+
+                public long Length
+                {
+                    get
+                    {
+                        throw new NotImplementedException();
+                    }
+                }
+
+                public string Name
+                {
+                    get
+                    {
+                        throw new NotImplementedException();
+                    }
+                }
+
+                public string PhysicalPath
+                {
+                    get
+                    {
+                        throw new NotImplementedException();
+                    }
+                }
+
+                public Stream CreateReadStream()
+                {
+                    throw new NotImplementedException();
+                }
+            }
         }
 
         private sealed class TestFileInfo : IFileInfo