int digits = RANDOM_SOURCE.nextInt(numBits);
    if (digits == 0) {
      return new BigInteger(1, RANDOM_SOURCE);
    } else {
      return new BigInteger(digits, RANDOM_SOURCE).setBit(digits);
    }
  }

  /**
   * Equivalent to calling randomPositiveBigInteger(numBits) and then flipping the sign with 50%
   * probability.
   */
  static BigInteger randomNonZeroBigInteger(int numBits) {

    int digits = RANDOM_SOURCE.nextInt(numBits);
    if (digits == 0) {
      return new BigInteger(1, RANDOM_SOURCE);
    } else {
      return new BigInteger(digits, RANDOM_SOURCE).setBit(digits);
    }
  }

  /**
   * Equivalent to calling randomPositiveBigInteger(numBits) and then flipping the sign with 50%
   * probability.
   */
  static BigInteger randomNonZeroBigInteger(int numBits) {

        assertThat(ZERO.setBit(result)).isAtMost(x);
        assertThat(ZERO.setBit(result + 1)).isGreaterThan(x);
      }
    }
  }

  public void testLog2Ceiling() {
    for (BigInteger x : POSITIVE_BIGINTEGER_CANDIDATES) {
      for (RoundingMode mode : asList(CEILING, UP)) {
        int result = BigIntegerMath.log2(x, mode);
        assertThat(ZERO.setBit(result)).isAtLeast(x);

    for (long value : TEST_LONGS) {
      BigInteger expected =
          (value >= 0)
              ? BigInteger.valueOf(value)
              : BigInteger.valueOf(value).add(BigInteger.ZERO.setBit(64));
      assertWithMessage(UnsignedLongs.toString(value))
          .that(UnsignedLong.fromLongBits(value).bigIntegerValue())
          .isEqualTo(expected);
    }
  }

  public void testValueOfLong() {

   *
   * @throws IllegalArgumentException if {@code x <= 0}
   * @since 20.0
   */
  public static BigInteger ceilingPowerOfTwo(BigInteger x) {
    return BigInteger.ZERO.setBit(log2(x, CEILING));
  }

  /**
   * Returns the largest power of two less than or equal to {@code x}. This is equivalent to {@code
   * BigInteger.valueOf(2).pow(log2(x, FLOOR))}.
   *

    assertThat(UnsignedLongs.parseUnsignedLong("1234567890abcdef", 16))
        .isEqualTo(0x1234567890abcdefL);
  }

  public void testParseLongWithRadixLimits() {
    BigInteger max = BigInteger.ZERO.setBit(64).subtract(ONE);
    // loops through all legal radix values.
    for (int r = Character.MIN_RADIX; r <= Character.MAX_RADIX; r++) {
      int radix = r;

  public BigInteger bigIntegerValue() {
    BigInteger bigInt = BigInteger.valueOf(value & UNSIGNED_MASK);
    if (value < 0) {
      bigInt = bigInt.setBit(Long.SIZE - 1);
    }
    return bigInt;
  }

  @Override
  public int compareTo(UnsignedLong o) {
    checkNotNull(o);
    return UnsignedLongs.compare(value, o.value);
  }

  @Override

    assertThat(UnsignedLongs.parseUnsignedLong("1234567890abcdef", 16))
        .isEqualTo(0x1234567890abcdefL);
  }

  public void testParseLongWithRadixLimits() {
    BigInteger max = BigInteger.ZERO.setBit(64).subtract(ONE);
    // loops through all legal radix values.
    for (int r = Character.MIN_RADIX; r <= Character.MAX_RADIX; r++) {
      int radix = r;

  }

  @GwtIncompatible // BigIntegerMath // TODO(cpovirk): GWT-enable BigIntegerMath
  public void testConstantMaxPowerOfSqrt2Unsigned() {
    assertEquals(
        /* expected= */ BigIntegerMath.sqrt(BigInteger.ZERO.setBit(2 * Integer.SIZE - 1), FLOOR)
            .intValue(),
        /* actual= */ IntMath.MAX_POWER_OF_SQRT2_UNSIGNED);
  }

  @GwtIncompatible // pow()
  public void testConstantsPowersOf10() {

  }

  @GwtIncompatible // BigIntegerMath // TODO(cpovirk): GWT-enable BigIntegerMath
  public void testConstantMaxPowerOfSqrt2Unsigned() {
    assertEquals(
        /* expected= */ BigIntegerMath.sqrt(BigInteger.ZERO.setBit(2 * Integer.SIZE - 1), FLOOR)
            .intValue(),
        /* actual= */ IntMath.MAX_POWER_OF_SQRT2_UNSIGNED);
  }

  @GwtIncompatible // pow()
  public void testConstantsPowersOf10() {