this.sink = sink
    }

    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.acceptFrame() // PING
    peer.play()

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

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