clientListener.assertFailure(
      101,
      null,
      ProtocolException::class.java,
      "Expected 'Connection' header value 'Upgrade' but was 'null'",
    )
    webSocket.cancel()
  }

  @Test
  @Throws(IOException::class)
  fun wrongConnectionHeader() {
    webServer.enqueue(
      MockResponse.Builder()
        .code(101)
        .setHeader("Upgrade", "websocket")

      webSocketCloseTimeout: Long = RealWebSocket.CANCEL_AFTER_CLOSE_MILLIS,
    ) {
      val url = "http://example.com/websocket"
      val response =
        Response.Builder()
          .code(101)
          .message("OK")
          .request(Request.Builder().url(url).build())
          .headers(responseHeaders!!)
          .protocol(Protocol.HTTP_1_1)
          .build()
      webSocket =

    return true
  }

  @Throws(IOException::class)
  internal fun checkUpgradeSuccess(
    response: Response,
    exchange: Exchange?,
  ) {
    if (response.code != 101) {
      throw ProtocolException(
        "Expected HTTP 101 response but was '${response.code} ${response.message}'",
      )
    }

    val headerConnection = response.header("Connection")

    containing an IP address we must match that address against the URL's IP address, even when the
    two addresses are encoded differently, such as `192.168.1.1` and `0::0:0:FFFF:C0A8:101`. Note
    that OkHttp incorrectly rejected valid certificates resulting in a failure to connect; at no
    point were invalid certificates accepted.