public void RenameNewFileWithNumericPrefix()
            {
                var newFile = new FileInfo(@"c:\test\2SomeNewFile.mp3");
                int newIndex = 5;
                int digitCount = 3;

                var renamer = new FileRenamer();
                var newName = renamer.GetNewFileName(newFile, newIndex, digitCount);

                newName.ShouldBe("005-2SomeNewFile.mp3");
            }
            public void RenameExistingFileSameDigitCount()
            {
                var newFile = new FileInfo(@"c:\test\002-SomeNewFile.mp3");
                int newIndex = 5;
                int digitCount = 3;

                var renamer = new FileRenamer();
                var newName = renamer.GetNewFileName(newFile, newIndex, digitCount);

                newName.ShouldBe("005-SomeNewFile.mp3");
            }