private var port = 0
  private val executor = Executors.newSingleThreadExecutor(threadFactory("MockHttp2Peer"))
  private var serverSocket: ServerSocket? = null
  private var socket: Socket? = null

  fun setClient(client: Boolean) {
    if (this.client == client) return
    this.client = client
    writer = Http2Writer(bytesOut, client)
  }

  fun acceptFrame() {
    frameCount++
  }

   * that we have to flush headers immediately before any request body can be sent.
   * https://github.com/square/okhttp/issues/2543
   */
  @Test fun peerSetsZeroFlowControl() {
    peer.setClient(true)

    // Write the mocking script.
    peer.sendFrame().settings(Settings().set(Settings.INITIAL_WINDOW_SIZE, 0))
    peer.acceptFrame() // ACK