for (long value : TEST_LONGS) {
      assertWithMessage(UnsignedLongs.toString(value))
          .that(UnsignedLong.fromLongBits(value).longValue())
          .isEqualTo(value);
    }
  }

  public void testAsUnsignedBigIntegerValue() {
    for (long value : TEST_LONGS) {
      BigInteger expected =
          (value >= 0)
              ? BigInteger.valueOf(value)
              : BigInteger.valueOf(value).add(BigInteger.ZERO.setBit(64));