assertThat(UnsignedLongs.divide(0xfffffffffffffffeL, 0xfffffffffffffffdL)).isEqualTo(1);
    assertThat(UnsignedLongs.divide(0xfffffffffffffffdL, 0xfffffffffffffffeL)).isEqualTo(0);
    assertThat(UnsignedLongs.divide(0xfffffffffffffffeL, 65535)).isEqualTo(281479271743488L);
    assertThat(UnsignedLongs.divide(0xfffffffffffffffeL, 2)).isEqualTo(0x7fffffffffffffffL);

   * unless the user is actually calling a parse method.
   */
  private static final class ParseOverflowDetection {
    private ParseOverflowDetection() {}

    // calculated as 0xffffffffffffffff / radix
    static final long[] maxValueDivs = new long[Character.MAX_RADIX + 1];
    static final int[] maxValueMods = new int[Character.MAX_RADIX + 1];

    } else if (frameLength == PAYLOAD_LONG.toLong()) {
      frameLength = source.readLong()
      if (frameLength < 0L) {
        throw ProtocolException(
          "Frame length 0x${frameLength.toHexString()} > 0x7FFFFFFFFFFFFFFF",
        )
      }
    }

    if (isControlFrame && frameLength > PAYLOAD_BYTE_MAX) {
      throw ProtocolException("Control frame must be less than ${PAYLOAD_BYTE_MAX}B.")
    }

    assertFailsWith<ProtocolException> {
      clientReader.processNextFrame()
    }.also { expected ->
      assertThat(expected.message).isEqualTo(
        "Frame length 0x8000000000000000 > 0x7FFFFFFFFFFFFFFF",
      )
    }
  }

  @Test fun serverHelloTwoChunks() {
    data.write("818537fa213d7f9f4d".decodeHex()) // Hel
    data.write("5158".decodeHex()) // lo
    serverReader.processNextFrame()