Widget buildPageViewTest(TickerProvider tickerProvider) {
  var colors = [
    [Colors.blue[800], Colors.orange],
    [Colors.green[800], Colors.red]
  ];
  const int CYCLES = 20;
  int numPages = 2;
  Random rnd = Random();
  Stream<int> stream = Stream.periodic(Duration(seconds: 3))
      .map((_) => numPages += 1 + rnd.nextInt(2))
      .take(CYCLES);

  AnimationController animation = AnimationController(
    vsync: tickerProvider,
    duration: Duration(seconds: 3 * CYCLES),
    upperBound: CYCLES.toDouble(),
  );
  animation.forward();

  return Column(
    children: <Widget>[
      RotationTransition(
        turns: animation,
        child: Icon(
          Icons.refresh,
          size: 100.0,
        ),
      ),
      StreamBuilder(
        stream: stream,
        initialData: 1,
        builder: (BuildContext context, AsyncSnapshot<int> snapshot) {
          int itemCount = snapshot.data;
          print("StreamBuilder itemCount: $itemCount");
          return Expanded(
            child: PageView.builder(
              itemCount: itemCount,
              itemBuilder: (ctx, idx) {
                return AnimatedSwitcher(
                  duration: Duration(milliseconds: 500),
                  child: Text(
                    idx == itemCount - 1
                        ? "last page"
                        : "page\n${idx + 1} of $itemCount",
                    key: ValueKey<String>("$idx:$itemCount"),
                    textAlign: TextAlign.center,
                    style: TextStyle(
                      color: colors[itemCount % 2][idx % 2],
                      fontSize: 80.0,
                      fontWeight: FontWeight.bold,
                    ),
                  ),
                );
              },
            ),
          );
        },
      ),
    ],
  );
}