Fixing test issue when Linux always returns / for PathGetPathRoot (when its rooted)

http://typedescriptor.net/browse/members/1247454-Mono.Unix.UnixPath.GetPathRoot%28String%29

NzbDrone.Common/DiskProvider.cs

@@ -294,25 +294,25 @@ namespace NzbDrone.Common
         {
             Ensure.That(() => path).IsValidPath();
 
-            var root = GetPathRoot(path);
-
-            if (!FolderExists(root))
-                throw new DirectoryNotFoundException(root);
-
             if (OsInfo.IsLinux)
             {
-                var driveInfo = DriveInfo.GetDrives().SingleOrDefault(c => c.IsReady && c.Name.Equals(root, StringComparison.CurrentCultureIgnoreCase));
+                var driveInfo = DriveInfo.GetDrives().SingleOrDefault(c => c.IsReady && path.StartsWith(c.Name, StringComparison.CurrentCultureIgnoreCase));
 
                 if (driveInfo == null)
                 {
-                    return 0;
+                    throw new DirectoryNotFoundException(path);
                 }
 
-                return driveInfo.AvailableFreeSpace;
+             return driveInfo.AvailableFreeSpace;
             }
 
+            var root = GetPathRoot(path);
+
+            if (!FolderExists(root))
+                throw new DirectoryNotFoundException(root);
+
             return DriveFreeSpaceEx(root);
-        }
+           }
 
         private static long DriveFreeSpaceEx(string folderName)
         {

NzbDrone.Core.Test/ProviderTests/DiskProviderTests/FreeDiskSpaceFixture.cs

@@ -8,7 +8,7 @@ using NzbDrone.Test.Common;
 namespace NzbDrone.Core.Test.ProviderTests.DiskProviderTests
 {
     [TestFixture]
-    public class FreeDiskSpaceTest : CoreTest<DiskProvider>
+    public class FreeDiskSpaceFixture : CoreTest<DiskProvider>
     {
         [Test]
         public void should_return_free_disk_space()