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.
Scheduler.unstable_yieldValue('Foo');
      return (
        <Suspense fallback={<Text text="Initial load..." />}>
          <Suspense
            unstable_avoidThisFallback={true}
            fallback={<Text text="Updating..." />}>
            <AsyncText text="A" ms={5000} />
            {showC ? <AsyncText text="C" ms={5000} /> : null}
          </Suspense>
          <Text text="B" />
        </Suspense>
      );
    }
    ReactNoop.render(<Foo />);
    expect(Scheduler).toFlushAndYield([
      'Foo',
      'Suspend! [A]',
      'B',
      'Initial load...',
    ]);
    expect(ReactNoop.getChildren()).toEqual([span('Initial load...')]);
    
    Scheduler.unstable_advanceTime(5000);
    await advanceTimers(5000);
    expect(Scheduler).toHaveYielded(['Promise resolved [A]']);