for (BigInteger x : NEGATIVE_BIGINTEGER_CANDIDATES) {
      assertThrows(IllegalArgumentException.class, () -> BigIntegerMath.ceilingPowerOfTwo(x));
    }
  }

  public void testFloorPowerOfTwoNegative() {
    for (BigInteger x : NEGATIVE_BIGINTEGER_CANDIDATES) {
      assertThrows(IllegalArgumentException.class, () -> BigIntegerMath.floorPowerOfTwo(x));
    }
  }

  public void testCeilingPowerOfTwoZero() {