assertTrue(result == 0 || TEN.pow(2 * result - 1).compareTo(x2) < 0);
    }
  }

  // Relies on the correctness of log10(BigInteger, {HALF_UP,HALF_DOWN}).
  @GwtIncompatible // TODO
  public void testLog10HalfEven() {
    for (BigInteger x : POSITIVE_BIGINTEGER_CANDIDATES) {
      int halfEven = BigIntegerMath.log10(x, HALF_EVEN);
      // Now figure out what rounding mode we should behave like (it depends if FLOOR was