Answer to StackOverflow Question

I know the title is really bad, but I'm just now sure how to explain the situation. Feel free to suggest a better title and I'll change it.

So I just starting to get into testing for the first time, and I'm using Jest. was doing okay till I ran into a construction like this

function f(n) {
	let g;
	if (n === 1) {
		g = () => console.log(`ok`);
	} else {
		g = () => {throw `not okay`;};
	}

	someEvent.listen(async () => {
		g();
	});
}

I'm stuck on how to test that, when I put in something other than 1 to f, it will throw not okay. From what I gather, just the simplest expect(...).toBe(...) will work if the callback to the event isn't async, but I haven't been able to figure out how to do it with it being async.