source.timeout().timeout(1000, TimeUnit.MILLISECONDS)
    assertThat(source.readByte()).isEqualTo('A'.code.toByte())
    assertThat(source.readByte()).isEqualTo('B'.code.toByte())
    assertThat(source.readByte()).isEqualTo('C'.code.toByte())
    assertFailsWith<SocketTimeoutException> {
      source.readByte() // If Content-Length was accurate, this would return -1 immediately.
    }
    source.close()
  }

pkg io, method (*SectionReader) Size() int64
pkg io, type ByteReader interface { ReadByte }
pkg io, type ByteReader interface, ReadByte() (uint8, error)
pkg io, type ByteScanner interface { ReadByte, UnreadByte }
pkg io, type ByteScanner interface, ReadByte() (uint8, error)
pkg io, type ByteScanner interface, UnreadByte() error
pkg io, type Closer interface { Close }

// has been used.
// The returned reader contains the payload.
func waitForHTTPResponse(respBody io.Reader) (io.Reader, error) {
	reader := bufio.NewReader(respBody)
	for {
		b, err := reader.ReadByte()
		if err != nil {
			return nil, err
		}
		// Check if we have a response ready or a filler byte.
		switch b {
		case 0:
			return reader, nil
		case 1:
			errorText, err := io.ReadAll(reader)

    val bodySource = response.body.source()
    assertThat(bodySource.readByte()).isEqualTo('d'.code.toByte())

    // The second byte of this request will be delayed by 750ms so we should time out after 250ms.
    val startNanos = System.nanoTime()
    bodySource.use {
      assertFailsWith<IOException> {
        bodySource.readByte()
      }.also { expected ->
        // Timed out as expected.