}
    }

    fun listener(listener: Listener) =
      apply {
        this.listener = listener
      }

    fun pushObserver(pushObserver: PushObserver) =
      apply {
        this.pushObserver = pushObserver
      }

    fun pingIntervalMillis(pingIntervalMillis: Int) =
      apply {
        this.pingIntervalMillis = pingIntervalMillis
      }

    peer: MockHttp2Peer,
    pushObserver: PushObserver = IGNORE,
    listener: Http2Connection.Listener = Http2Connection.Listener.REFUSE_INCOMING_STREAMS,
  ): Http2Connection {
    val connection =
      Http2Connection
        .Builder(true, TaskRunner.INSTANCE)
        .socket(peer.openSocket().asBufferedSocket(), "peer")
        .pushObserver(pushObserver)
        .listener(listener)
        .build()

    peer.play()

    // Play it back.
    val connection =
      Http2Connection
        .Builder(true, TaskRunner.INSTANCE)
        .socket(peer.openSocket().asBufferedSocket(), "peer")
        .pushObserver(Http2ConnectionTest.IGNORE)
        .listener(realConnection)
        .build()
    connection.start(sendConnectionPreface = false)

    // verify the peer received the ACK
    val ackFrame = peer.takeFrame()