}
  }

  public void testCeilingPowerOfTwoZero() {
    assertThrows(
        IllegalArgumentException.class, () -> BigIntegerMath.ceilingPowerOfTwo(BigInteger.ZERO));
  }

  public void testFloorPowerOfTwoZero() {
    assertThrows(
        IllegalArgumentException.class, () -> BigIntegerMath.floorPowerOfTwo(BigInteger.ZERO));
  }

      }
    }
  }

  public void testFloorPowerOfTwo() {
    for (int x : POSITIVE_INTEGER_CANDIDATES) {
      BigInteger expectedResult = BigIntegerMath.floorPowerOfTwo(BigInteger.valueOf(x));
      assertEquals(expectedResult.intValue(), IntMath.floorPowerOfTwo(x));
    }
  }

  public void testCeilingPowerOfTwoNegative() {
    for (int x : NEGATIVE_INTEGER_CANDIDATES) {

   * BigInteger.valueOf(2).pow(log2(x, FLOOR))}.
   *
   * @throws IllegalArgumentException if {@code x <= 0}
   * @since 20.0
   */
  public static BigInteger floorPowerOfTwo(BigInteger x) {
    return BigInteger.ZERO.setBit(log2(x, FLOOR));
  }

  /** Returns {@code true} if {@code x} represents a power of two. */
  public static boolean isPowerOfTwo(BigInteger x) {
    checkNotNull(x);

   * checkedPow(2, log2(x, FLOOR))}.
   *
   * @throws IllegalArgumentException if {@code x <= 0}
   * @since 20.0
   */
  public static long floorPowerOfTwo(long x) {
    checkPositive("x", x);

    // Long.highestOneBit was buggy on GWT.  We've fixed it, but I'm not certain when the fix will
    // be released.