assertTrue(ZERO.setBit(result).compareTo(x) <= 0);
        assertTrue(ZERO.setBit(result + 1).compareTo(x) > 0);
      }
    }
  }

  public void testLog2Ceiling() {
    for (BigInteger x : POSITIVE_BIGINTEGER_CANDIDATES) {
      for (RoundingMode mode : asList(CEILING, UP)) {
        int result = BigIntegerMath.log2(x, mode);
        assertTrue(ZERO.setBit(result).compareTo(x) >= 0);

        assertTrue(ZERO.setBit(result).compareTo(x) <= 0);
        assertTrue(ZERO.setBit(result + 1).compareTo(x) > 0);
      }
    }
  }

  public void testLog2Ceiling() {
    for (BigInteger x : POSITIVE_BIGINTEGER_CANDIDATES) {
      for (RoundingMode mode : asList(CEILING, UP)) {
        int result = BigIntegerMath.log2(x, mode);
        assertTrue(ZERO.setBit(result).compareTo(x) >= 0);

    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() {

    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 radix = Character.MIN_RADIX; radix <= Character.MAX_RADIX; radix++) {
      // tests can successfully parse a number string with this radix.

    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 radix = Character.MIN_RADIX; radix <= Character.MAX_RADIX; radix++) {
      // tests can successfully parse a number string with this radix.

  }

  @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 // TODO
  public void testConstantMaxPowerOfSqrt2Unsigned() {
    assertEquals(
        /*expected=*/ BigIntegerMath.sqrt(BigInteger.ZERO.setBit(2 * Long.SIZE - 1), FLOOR)
            .longValue(),
        /*actual=*/ LongMath.MAX_POWER_OF_SQRT2_UNSIGNED);
  }

  @GwtIncompatible // BigIntegerMath // TODO(cpovirk): GWT-enable BigIntegerMath

  }

  @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() {