return failFastResponse!!
    }

    val result = responseQueue.take()

    // If take() returned because we're shutting down, then enqueue another dead letter so that any
    // other threads waiting on take() will also return.
    if (result == DEAD_LETTER) responseQueue.add(DEAD_LETTER)

    return result
  }

  override fun peek(): MockResponse {
    return responseQueue.peek() ?: failFastResponse ?: super.peek()
  }

    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

    /** The next byte to read. This is always less than or equal to [upstreamPos]. */
    private var sourcePos = 0L

    /**
     * Selects where to find the bytes for a read and read them. This is one of three sources.
     *
     * ## Upstream
     *
     * In this case the current thread is assigned as the upstream reader. We read bytes from

    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)

 *  Upgrade: [Kotlin 1.8.21][kotlin_1_8_21].


## Version 4.11.0

_2023-04-22_

 *  Fix: Don't fail the call when the response code is ‘HTTP 102 Processing’ or
    ‘HTTP 103 Early Hints’.
 *  Fix: Read the response even if writing the request fails. This means you'll get a proper HTTP
    response even if the server rejects your request body.
 *  Fix: Use literal IP addresses directly rather than passing them to `DnsOverHttps`.

   * 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
  }