An update to Test inside a test was not wrapped in act. With v5.0.1

[vladwhd]

Issue description

With the latest version of the library and with the latest RN I get the following error in the console:

Cannot log after tests are done. Did you forget to wait for something async in your test?
Attempted to log "Warning: An update to Test inside a test was not wrapped in act(...).

When testing, code that causes React state updates should be wrapped into act(...):

There is more output in the console, but this is essential I think. Not sure if it is really related to #25

Also, test is marked as successful.

With @testing-library/react an equivalent test in a web app project causes no problems at all.

How to reproduce

npx react-native init TestApp
npm i --save-dev @testing-library/react-native

Create a Test.test.js inside of __tests__ with following content:

import React, {useEffect, useState} from 'react';
import {Text, View} from 'react-native';
import {render} from '@testing-library/react-native';

const Test = () => {
    const [v, setV] = useState(1);
    useEffect(()=>{
        setTimeout(() => {
            setV(2);
        }, 0)
    }, []);
    return <View><Text>{v}</Text></View>
};
test('Test', () => {
    render(<Test />);
});

Then npm run test

Versions

• react-native or expo: react-native
• native-testing-library version: 5.0.1
• jest-preset: @testing-library/react-native
• react-native version: 0.61.3
• node version: v13.2.0

[bcarroll22]

Hi thanks for the issue. I don't think it's related to #25, but it is probably related to testing-library/react-testing-library#535. We should stay subscribed to that issue here.

Related, what version of React do you have installed? The reason I ask is that react native 0.61.3 requires react: 16.9.0 (explicitly, no other version is supported) so this shouldn't be related to a version bump of testing library since act comes from React. Are you by chance using a later version of React and React Test Renderer?

[vladwhd]

I'm using 16.9.0 of React. Just tried to update to react@latest and got 16.12.0. Looks like it didn't change anything for this error.
Feels like it's useEffect that is not handled properly. Because I have no problems with example (https://testing-library.com/docs/native-testing-library/example-intro). I'll keep investigating on Monday :)

[bcarroll22]

This should fix it for you. The issue is not cleaning up the timeout.

const Test = () => {
  const [v, setV] = React.useState(1);
  React.useEffect(()=>{
    const timeout = setTimeout(() => setV(2), 0);
    return () => clearTimeout(timeout);
  }, []);
  return <View><Text>{v}</Text></View>
};
test('Test', () => {
  render(<Test />);
});

[vladwhd]

Yes, it was this indeed, thank you very much!