} else if (b != 0) {
      // Group separator ":" delimiter.
      if (input.startsWith(":", startIndex = i)) {
        i++
      } else if (input.startsWith(".", startIndex = i)) {
        // If we see a '.', rewind to the beginning of the previous group and parse as IPv4.
        if (!decodeIpv4Suffix(input, groupOffset, limit, address, b - 2)) return null
        b += 2 // We rewound two bytes and then added four.
        break

      )

    assertFailsWith<EOFException> {
      parts.nextPart()
    }
  }

  /** Confirm that [MultipartBody] and [MultipartReader] can work together. */
  @Test fun `multipart round trip`() {
    val body =
      MultipartBody.Builder("boundary")
        .setType(MultipartBody.PARALLEL)
        .addPart("Quick".toRequestBody("text/plain".toMediaType()))
        .addFormDataPart("color", "Brown")