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()