assertTrue(BigIntegerMath.isPowerOfTwo(result));
      assertThat(result).isAtMost(x);
      assertThat(result.add(result)).isGreaterThan(x);
    }
  }

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