@Test
  fun upgrade() {
    val socketHandler =
      MockSocketHandler()
        .apply {
          receiveRequest("client says hello\n")
          sendResponse("server says hello\n")
          receiveRequest("client says goodbye\n")
          sendResponse("server says goodbye\n")
          exhaustResponse()
          exhaustRequest()
        }
    server.enqueue(socketHandler.upgradeResponse())

    client

      val bodyDelayNanos = response.bodyDelayNanos
      val trailers = response.trailers
      val body = response.body
      val socketHandler = response.socketHandler
      val outFinished = (
        body == null &&
          response.pushPromises.isEmpty() &&
          socketHandler == null
      )
      val flushHeaders = body == null || bodyDelayNanos != 0L
      require(!outFinished || trailers.size == 0) {

import java.io.IOException
import java.util.concurrent.CountDownLatch
import java.util.concurrent.FutureTask
import java.util.concurrent.LinkedBlockingQueue
import java.util.concurrent.TimeUnit
import mockwebserver3.SocketHandler
import okhttp3.internal.connection.BufferedSocket
import okhttp3.internal.connection.asBufferedSocket
import okio.Socket
import okio.utf8Size

private typealias Action = (BufferedSocket) -> Unit

/**