How to “pump” in Flutter

Don’t let your widgets standstill

When I first tried Flutter, widget testing was the part that confused me the most mainly because it runs on a fake clock and “time” becomes strange.

Know how to pump, don’t be like Steve.

Let’s use this repository/demo app for demonstration:

tianhaoz95/explain-flutter-async-widget-test-2-3yo

Time doesn’t flow until you pump

Flutter widget testing, at first glance, looks like Jest, but if you naively migrate Jest testing philosophy, you will find that your widget never rebuild.

If you are coming from Jest, you will probably find this code completely okay: