return EventSource.Factory { request, listener ->
      val actualRequest =
        if (request.header("Accept") == null) {
          request.newBuilder().addHeader("Accept", "text/event-stream").build()
        } else {
          request
        }

      RealEventSource(actualRequest, listener).apply {
        connect(callFactory)
      }
    }
  }

  @JvmStatic

     * asynchronous process to connect the socket. Once that succeeds or fails, `listener` will be
     * notified. The caller must cancel the returned event source when it is no longer in use.
     */
    fun newEventSource(
      request: Request,
      listener: EventSourceListener,
    ): EventSource
  }

![Events Diagram](../assets/images/******@****.***)

Here’s a [sample event listener](https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/PrintEventsNonConcurrent.java) that prints each event with a timestamp.

```java
class PrintingEventListener extends EventListener {

  @RegisterExtension
  @JvmField
  var clientTestRule = OkHttpClientTestRule()

  private val listener = RecordingEventListener()
  private val handshakeCertificates = platform.localhostHandshakeCertificates()

  private var client =
    clientTestRule.newClientBuilder()
      .eventListenerFactory(clientTestRule.wrap(listener))
      .build()

  private lateinit var server: MockWebServer

  @BeforeEach

    }
  }

  /** See https://api.slack.com/rtm. */
  public WebSocket rtm(HttpUrl url, WebSocketListener listener) {
    return httpClient.newWebSocket(new Request.Builder()
        .url(url)
        .build(), listener);
  }

  static final class SlackJsonAdapters {
    @ToJson String urlToJson(HttpUrl httpUrl) {
      return httpUrl.toString();
    }

        ).setHeader("content-type", "text/event-stream")
        .build(),
    )
    val source = newEventSource()
    assertThat(source.request().url.encodedPath).isEqualTo("/")
    listener.assertOpen()
    listener.assertEvent(null, null, "hey")
    listener.assertClose()
  }

  @RetryingTest(5)
  fun cancelInEventShortCircuits() {
    server.enqueue(
      MockResponse.Builder()
        .body(
          """

        listener.onFailure(this, IOException("canceled"), response)
      } else {
        listener.onClosed(this)
      }
    }
  }

  private fun ResponseBody.isEventStream(): Boolean {
    val contentType = contentType() ?: return false
    return contentType.type == "text" && contentType.subtype == "event-stream"
  }

  override fun onFailure(
    call: Call,
    e: IOException,
  ) {

  ) {
  }

  /**
   * TODO description.
   *
   * No further calls to this listener will be made.
   */
  open fun onClosed(eventSource: EventSource) {
  }

  /**
   * Invoked when an event source has been closed due to an error reading from or writing to the
   * network. Incoming events may have been lost. No further calls to this listener will be made.
   */
  open fun onFailure(
    eventSource: EventSource,

 */
class AutobahnTester {
  val client = OkHttpClient()

  private fun newWebSocket(
    path: String,
    listener: WebSocketListener,
  ): WebSocket {
    val request =
      Request.Builder()
        .url(HOST + path)
        .build()
    return client.newWebSocket(request, listener)
  }

  fun run() {
    try {
      val count = getTestCount()
      println("Test count: $count")

  return discovered.getEngineTestDescriptor(testEngine).descendants.toList()
}

/**
 * Builds the awkwardly package private TreePrintingListener listener which we would like to use
 * from ConsoleLauncher.
 *
 * https://github.com/junit-team/junit5/issues/2469
 */
fun treeListener(): TestExecutionListener {
  val colorPalette =