assertThrows(NumberFormatException.class, () -> UnsignedLongs.parseUnsignedLong("0", -1));
  }

  public void testToString() {
    String[] tests = {
      "0",
      "ffffffffffffffff",
      "7fffffffffffffff",
      "ff1a618b7f65ea12",
      "5a4316b8c153ac4d",
      "6cf78a4b139a4e2a"
    };
    int[] bases = {2, 5, 7, 8, 10, 16};
    for (int base : bases) {
      for (String x : tests) {

   * unless the user is actually calling a parse method.
   */
  private static final class ParseOverflowDetection {
    private ParseOverflowDetection() {}

    // calculated as 0xffffffffffffffff / radix
    static final long[] maxValueDivs = new long[Character.MAX_RADIX + 1];
    static final int[] maxValueMods = new int[Character.MAX_RADIX + 1];