https://codesandbox.io/s/upbeat-frost-3tt25

1. Press Suspend, see "Loading..."
2. Wait five seconds, you'll see "Happy birthday" at some point 
3. You won't see it again no matter how long you wait

Expected: you'll see it every five seconds.
expect(ReactNoop.getChildren()).toEqual([span('Hi!'), span('A')]);
    Scheduler.unstable_advanceTime(1800);
    await advanceTimers(1800);
    expect(Scheduler).toFlushAndYield([]);
    
    expect(ReactNoop.getChildren()).toEqual([span('Hi!'), span('A')]);
    Scheduler.unstable_advanceTime(1500);
    await advanceTimers(1500);
    expect(Scheduler).toHaveYielded(['Promise resolved [B]']);
    expect(ReactNoop.getChildren()).toEqual([
      span('Hi!'),
      hiddenSpan('A'),
      span('Loading B...'),
    ]);
  });
  it('withSuspenseConfig timeout applies when we use a newly created avoided boundary', async () => {
    function App({page}) {
      return (
        <Suspense fallback={<Text text="Loading..." />}>
          <Text text="Hi!" />
          {page === 'A' ? (
            <Text text="A" />
          ) : (
            <Suspense
              fallback={<Text text={'Loading ' + page + '...'} />}
              unstable_avoidThisFallback={true}>
              <AsyncText text={page} ms={3000} />
            </Suspense>
          )}