drive

1 assertEqual(WindowsPath("").drive, "");
2 assertEqual(WindowsPath("/Hello/World").drive, "");
3 assertEqual(WindowsPath("C:/Hello/World").drive, "C:");
4 assertEqual(PosixPath("").drive, "");
5 assertEqual(PosixPath("/Hello/World").drive, "");
6 assertEqual(PosixPath("C:/Hello/World").drive, "");