public static String temporaryFileName(long nonce, String path) {
    return path + String.format(TEMPORARY_SUFFIX_FORMAT, nonce);
  }
@Test
  public void temporaryFileName() {
    assertEquals(PathUtils.temporaryFileName(1, "/"),
        PathUtils.temporaryFileName(1, "/"));
    assertNotEquals(PathUtils.temporaryFileName(1, "/"),
        PathUtils.temporaryFileName(2, "/"));
    assertNotEquals(PathUtils.temporaryFileName(1, "/"),
        PathUtils.temporaryFileName(1, "/a"));
  }