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

    // Confirm the events occur when expected.
    listener.takeEvent(CallStart::class.java, 0L)
    listener.takeEvent(ConnectionAcquired::class.java, applicationInterceptorDelay)
    listener.takeEvent(RequestHeadersStart::class.java, networkInterceptorDelay)
    listener.takeEvent(RequestHeadersEnd::class.java, 0L)
    listener.takeEvent(RequestBodyStart::class.java, 0L)
    listener.takeEvent(RequestBodyEnd::class.java, requestBodyDelay)

  /** Uses [request] to connect a new web socket. */
  override fun newWebSocket(
    request: Request,
    listener: WebSocketListener,
  ): WebSocket {
    val webSocket =
      RealWebSocket(
        taskRunner = taskRunner,
        originalRequest = request,
        listener = listener,
        random = Random(),
        pingIntervalMillis = pingIntervalMillis.toLong(),

    hand it off to another thread to write to it after `writeTo` returns.

    The `EventListener` may now see requests and responses interleaved in ways not previously
    permitted. For example, a listener may receive `responseHeadersStart()` followed by
    `requestBodyEnd()`, both on the same call. Such events may be triggered by different threads
    even for a single call.