@Override
  public void run() {
    synchronized (this) {
      serverPushClient.writeAndFlush('\r');
      serverPushClient.writeAndFlush('\n');
    }
    serverPushClient.scheduleHeartbeat();
  }
@Test
  public void run_reSchedulesHeartBeat() {
    underTest.run();

    verify(serverPushClient, times(2)).writeAndFlush(anyChar());
    verify(serverPushClient).scheduleHeartbeat();
  }