Add nativefilestream and several new methods to File and FileStream

System.IO.FileSystem.UnitTests/FileSystemUnitTestsBase.cs

@@ -0,0 +1,19 @@
+//
+// Copyright (c) .NET Foundation and Contributors
+// See LICENSE file in the project root for full license information.
+//
+
+using nanoFramework.TestFramework;
+
+namespace System.IO.FileSystem.UnitTests
+{
+    [TestClass]
+    public class FileSystemUnitTestsBase
+    {
+        internal const int _numberOfDrives = 4;
+        internal const string Root = @"D:\";
+
+        // set to true to wait for removable drive(s) to be mounted
+        internal const bool _waitForRemovableDrive = true;
+    }
+}