// x^2 >= 10^(2 * result - 1), or else we would have rounded down
      assertTrue(result == 0 || TEN.pow(2 * result - 1).compareTo(x2) <= 0);
    }
  }

  @GwtIncompatible // TODO
  public void testLog10HalfDown() {
    for (BigInteger x : POSITIVE_BIGINTEGER_CANDIDATES) {
      int result = BigIntegerMath.log10(x, HALF_DOWN);
      BigInteger x2 = x.pow(2);
      // x^2 <= 10^(2 * result + 1), or else we would have rounded up