how to mock delay expressions ?

[ilovett]

My state machine uses as delay expression: https://xstate.js.org/docs/guides/delays.html#delay-expressions-on-transitions

What is the best way to mock this time as elapsing or expression completing?

For most other async related code I have relied on flushing promises like so:

function flushPromises() {
  return new Promise((resolve) => setImmediate(resolve));
}

and in tests

// send an action

await flushPromises();

// verify state

I'm not really sure how to mock this though, is there some exact action I need to send or something else? What's the best way to do this?

[ilovett]

My bad. I just found the SimulatedClock.

[davidkpiano]

Relevant part of the docs: https://xstate.js.org/docs/guides/delays.html#interpretation