sourcePos += bytesToRead
        return bytesToRead
      }

      // Read from upstream. This always reads a full buffer: that might be more than what the
      // current call to Source.read() has requested.
      try {
        val upstreamBytesRead = upstream!!.read(upstreamBuffer, bufferMaxSize)

        // If we've exhausted upstream, we're done.

    val body = body("")
    val bytes = body.byteStream()
    assertThat(bytes.read()).isEqualTo(-1)
  }

  @Test
  fun byteStreamSeesBom() {
    val body = body("efbbbf68656c6c6f")
    val bytes = body.byteStream()
    assertThat(bytes.read()).isEqualTo(0xef)
    assertThat(bytes.read()).isEqualTo(0xbb)
    assertThat(bytes.read()).isEqualTo(0xbf)

  private var outputByteCount = 0L

  fun wrapInput(source: Source): Source {
    return object : ForwardingSource(source) {
      override fun read(
        sink: Buffer,
        byteCount: Long,
      ): Long {
        val result = super.read(sink, byteCount)
        if (result == -1L) return result
        inputByteCount += result
        return result
      }
    }
  }

    val derReader = DerReader(buffer)

    derReader.read("test") { header ->
      assertThat(header.tag).isEqualTo(16L)

      derReader.read("test") { header2 ->
        assertThat(header2.tag).isEqualTo(21L)
        assertThat(derReader.readOctetString()).isEqualTo("Smith".encodeUtf8())
      }

      derReader.read("test") { header3 ->
        assertThat(header3.tag).isEqualTo(1L)

   * a default value.
   *
   * If this does read a value, it starts with the tag and length, and reads an entire value,
   * including any potential composed values.
   *
   * If there's nothing to read and no default value, this will throw an exception.
   */
  fun fromDer(reader: DerReader): T

  fun fromDer(byteString: ByteString): T {

  var b = addressOffset

  var i = pos
  while (i < limit) {
    if (b == address.size) return false // Too many groups.

    // Read a delimiter.
    if (b != addressOffset) {
      if (input[i] != '.') return false // Wrong delimiter.
      i++
    }

    // Read 1 or more decimal digits for a value in 0..255.
    var value = 0
    val groupOffset = i
    while (i < limit) {
      val c = input[i]

    require(length < bytesOut.size - lastFrame.start)

    // Move everything from bytesOut into a new buffer.
    val fullBuffer = Buffer()
    bytesOut.read(fullBuffer, bytesOut.size)

    // Copy back all but what we're truncating.
    fullBuffer.read(bytesOut, lastFrame.start + length)
    outFrames.add(OutFrame(lastFrame.sequence, lastFrame.start, true))
    return writer
  }

    val inputStream = response.body.byteStream()
    assertThat(inputStream.read().toChar()).isEqualTo('A')
    call.cancel()
    assertFailsWith<IOException> {
      // Reading 'B' may succeed if it's buffered.
      inputStream.read()

      // But 'C' shouldn't be buffered (the response is throttled) and this should fail.
      inputStream.read()
    }
    inputStream.close()
  }

  @Test

    val terminalBitCount: Int

    /** Construct an internal node. */
    constructor() {
      this.children = arrayOfNulls(256)
      this.symbol = 0 // Not read.
      this.terminalBitCount = 0 // Not read.
    }

    /** Construct a terminal node. */
    constructor(symbol: Int, bits: Int) {
      this.children = null
      this.symbol = symbol
      val b = bits and 0x07

   */
  fun onFailure(
    call: Call,
    e: IOException,
  )

  /**
   * Called when the HTTP response was successfully returned by the remote server. The callback may
   * proceed to read the response body with [Response.body]. The response is still live until its
   * response body is [closed][ResponseBody]. The recipient of the callback may consume the response
   * body on another thread.
   *