### Question:
NativeIO { static native String getUserName(int uid) throws IOException;  static boolean isAvailable(); static native FileDescriptor open(String path, int flags, int mode); static native void chmod(String path, int mode); static void posixFadviseIfPossible(
      FileDescriptor fd, long offset, long len, int flags); static void syncFileRangeIfPossible(
      FileDescriptor fd, long offset, long nbytes, int flags); static Stat getFstat(FileDescriptor fd); static void renameTo(File src, File dst); static final int O_RDONLY; static final int O_WRONLY; static final int O_RDWR; static final int O_CREAT; static final int O_EXCL; static final int O_NOCTTY; static final int O_TRUNC; static final int O_APPEND; static final int O_NONBLOCK; static final int O_SYNC; static final int O_ASYNC; static final int O_FSYNC; static final int O_NDELAY; static final int POSIX_FADV_NORMAL; static final int POSIX_FADV_RANDOM; static final int POSIX_FADV_SEQUENTIAL; static final int POSIX_FADV_WILLNEED; static final int POSIX_FADV_DONTNEED; static final int POSIX_FADV_NOREUSE; static final int SYNC_FILE_RANGE_WAIT_BEFORE; static final int SYNC_FILE_RANGE_WRITE; static final int SYNC_FILE_RANGE_WAIT_AFTER; }### Answer:
@Test public void testGetUserName() throws IOException { assertFalse(NativeIO.getUserName(0).isEmpty()); }