Question

77

Testing React: Do not await the result of calling act(...) with sync logic

rated 0 times [ 82] [ 5] / answers: 1 / hits: 16772 / 5 Years ago, tue, september 17, 2019, 12:00:00

Using react and react-dom 16.9.0

I am getting this warning when I'm testing my react hooks:

console.error node_modules/react-dom/cjs/react-dom-test-utils.development.js:80

Warning: Do not await the result of calling act(...) with sync logic, it is not a Promise.

My test code (using jest with @testing-library/react)

...

await act( () => {

  rerender(

    <HookTester

      promise={asyncFunction}

      initialValue={'extra loading...'}

    />

  );

});



expect(asyncFunction).toHaveBeenCalledTimes(2);

...

But if I don't await, then my expectation would be done too early.

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carlton

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2 Years ago

answered 5 Years ago jocelynkarsynr · Accepted Answer

Oh! I got it!

It turns out the docs mention synchronous functions like this:

act( () => {

  // ... some 'sync logic'

});

which you can't await.

But you can await an async function of course:

await act( async () => {

  // ... some 'async logic'

});

This fixed the problem for me.