fun pingOnInterval() {
    client.initWebSocket(random, pingIntervalMillis = 500)
    taskFaker.advanceUntil(ns(500L))
    server.processNextFrame() // Ping.
    client.processNextFrame() // Pong.
    taskFaker.advanceUntil(ns(1000L))
    server.processNextFrame() // Ping.
    client.processNextFrame() // Pong.
    taskFaker.advanceUntil(ns(1500L))
    server.processNextFrame() // Ping.
    client.processNextFrame() // Pong.
  }