val elapsedUntilPong3 = System.nanoTime() - startNanos
    assertThat(TimeUnit.NANOSECONDS.toMillis(elapsedUntilPong3).toDouble())
      .isCloseTo(1500.0, 250.0)

    // The client pinged the server 3 times, and it has ponged back 3 times.
    assertThat(webSocket.sentPingCount()).isEqualTo(3)
    assertThat(server.receivedPingCount()).isEqualTo(3)
    assertThat(webSocket.receivedPongCount()).isEqualTo(3)