for (RoundingMode mode : ALL_ROUNDING_MODES) {
      assertThrows(IllegalArgumentException.class, () -> BigIntegerMath.log2(ZERO, mode));
    }
  }

  public void testLog2NegativeAlwaysThrows() {
    for (RoundingMode mode : ALL_ROUNDING_MODES) {
      assertThrows(
          IllegalArgumentException.class, () -> BigIntegerMath.log2(BigInteger.valueOf(-1), mode));
    }
  }