How should I test React Hook "useEffect" making an api call with Typescript?
Solution 1
There are two issues at play here
Asynchronous call to setData
setData
gets called in a Promise
callback.
As soon as a Promise
resolves, any callbacks waiting for it get queued in the PromiseJobs queue. Any pending jobs in the PromiseJobs queue run after the current message has completed and before the next one begins.
In this case the currently running message is your test so your test completes before the Promise
callback has a chance to run and setData
isn't called until after your test completes.
You can fix this by using something like setImmediate
to delay your assertions until after the callbacks in PromiseJobs have a chance to run.
Looks like you'll also need to call component.update()
to re-render the component with the new state. (I'm guessing this is because the state change happens outside of an act
since there isn't any way to wrap that callback code in an act
.)
All together, the working test looks like this:
it('should render a proper table data', done => {
const mock = new MockAdapter(axios);
mock.onGet('/path/to/api').reply(200, response.data);
const component = mount(<SalesPlanTable />);
setImmediate(() => {
component.update();
console.log(component.debug());
done();
});
});
Warning: An update to ... was not wrapped in act(...)
The warning is triggered by state updates to the component that happen outside of an act
.
State changes caused by asynchronous calls to setData
triggered by a useEffect
function will always happen outside of an act
.
Here is an extremely simple test that demonstrates this behavior:
import React, { useState, useEffect } from 'react';
import { mount } from 'enzyme';
const SimpleComponent = () => {
const [data, setData] = useState('initial');
useEffect(() => {
setImmediate(() => setData('updated'));
}, []);
return (<div>{data}</div>);
};
test('SimpleComponent', done => {
const wrapper = mount(<SimpleComponent/>);
setImmediate(done);
});
As I was searching for more info I stumbled on enzyme
issue #2073 opened just 10 hours ago talking about this same behavior.
I added the above test in a comment to help the enzyme
devs address the issue.
Solution 2
Solution
It both works and gets rid of the test was not wrapped in act(...)
warning.
const waitForComponentToPaint = async (wrapper) => {
await act(async () => {
await new Promise(resolve => setTimeout(resolve, 0));
wrapper.update();
});
};
Usage:
it('should do something', () => {
const wrapper = mount(<MyComponent ... />);
await waitForComponentToPaint(wrapper);
expect(wrapper).toBlah...
})
Thanks to...
This is a work-around suggested by edpark11 in the issue @Brian_Adams mentioned in his answer.
Original post: https://github.com/enzymejs/enzyme/issues/2073#issuecomment-565736674
I copied the post here with a few modifications for archiving sake.
Matt Berg
Updated on October 20, 2020Comments
-
Matt Berg over 3 years
I'm writing some jest-enzyme tests for a simple React app using Typescript and the new React hooks.
However, I can't seem to properly simulate the api call being made inside the
useEffect
hook.useEffect
makes the api call and updates theuseState
state "data" with "setData".The object "data" is then mapped into a table to its corresponding table cells.
This seems like it should be easy to tackle with a mocked api response and an enzyme mount, but I keep getting errors telling me to use
act()
for component updates.I tried using
act()
many ways but to no avail. I've tried replacingaxios
with fetch and using enzyme shallow and the react-test-library's render, but nothing seems to work.The component:
import axios from 'axios' import React, { useEffect, useState } from 'react'; interface ISUB { id: number; mediaType: { digital: boolean; print: boolean; }; monthlyPayment: { digital: boolean; print: boolean; }; singleIssue: { digital: boolean; print: boolean; }; subscription: { digital: boolean; print: boolean; }; title: string; } interface IDATA extends Array<ISUB> {} const initData: IDATA = []; const SalesPlanTable = () => { const [data, setData] = useState(initData); useEffect(() => { axios .get(`/path/to/api`) .then(res => { setData(res.data.results); }) .catch(error => console.log(error)); }, []); const renderTableRows = () => { return data.map((i: ISUB, k: number) => ( <tr key={k}> <td>{i.id}</td> <td> {i.title} </td> <td> {i.subscription.print} {i.mediaType.digital} </td> <td> {i.monthlyPayment.print} {i.monthlyPayment.digital} </td> <td> {i.singleIssue.print} {i.singleIssue.digital} </td> <td> <button>Submit</button> </td> </tr> )); }; return ( <table> <thead> <tr> <th>ID</th> <th>Name</th> <th>MediaType</th> <th>MonthlyPayment</th> <th>SingleIssue</th> <th/> </tr> </thead> <tbody'>{renderTableRows()}</tbody> </table> ); }; export default SalesPlanTable;
The test:
const response = { data: { results: [ { id: 249, mediaType: { digital: true, print: true }, monthlyPayment: { digital: true, print: true }, singleIssue: { digital: true, print: true }, subscription: { digital: true, print: true }, title: 'ELLE' } ] } }; //after describe it('should render a proper table data', () => { const mock = new MockAdapter(axios); mock.onGet('/path/to/api').reply(200, response.data); act(() => { component = mount(<SalesPlanTable />); }) console.log(component.debug()) });
I expect it to log the html of the table with the table body section rendered, I tried some async and different ways to mock
axios
but I keep either getting just the table headers or the message: An update toSalesPlanTable
inside a test was not wrapped inact(...).
I looked for many hours for a resolution but can't find anything that works so I decided to muster up some courage and ask here. -
Matt Berg about 5 yearsTHANK YOU SO MUCH!! It still has the weird 'act()' warning like you said but the table actually renders the proper data now, which is all I need... Hats off to you, sir!
-
Sebastian about 5 yearsUse
jest.useFakeTimers
and wrapjest.runAllImmediates
inact
. This way there is no more error: github.com/eps1lon/react-act-immediate/blob/…. I could not solve the original issue with this method though. -
Ben about 5 yearsTest passes, but still getting
Warning: An update to Post inside a test was not wrapped in act(...).
-
Arkanoid over 4 yearsI was able to remove the warning by wrapping the setImmediate in an
act
like so:await act(() => new Promise<void>((resolve) => { setImmediate(() => { node.update(); resolve(); }); }))