Jest mock a fetch function from a connected component - reactjs

Question

I have some code which works. However for my test I would like to mock the fetch that is done in the component.
The test
I am trying the following:
import ConnectedComponent from './Component';
import { render } from '#testing-library/react';
import user from '../__models__/user'; // arbitrary file for the response
// create a mock response
const mockSuccessResponse = user;
const mockJsonPromise = Promise.resolve(mockSuccessResponse);
const mockFetchPromise = Promise.resolve({
json: () => mockJsonPromise,
});
// Trying mock the refetch from http
jest.mock('./http', () => {
return {
refetch: () => ({
settingsFetch: () => mockFetchPromise,
})
}
});
it('renders', async () => {
const { getByText } = render(Component);
const title = await getByText('My title');
expect(title).toBeInTheDocument();
});
Error message
With this I receive the following error:
● Test suite failed to run
TypeError: (0 , _http.refetch)(...) is not a function
The Application code
This code is working fine in my application. To give you an example:
./http.js
import { connect } from 'react-refetch';
export async function fetchWithToken(urlOrRequest, options = {}) {
// some stuff
return response;
}
export const refetch = connect.defaults({
fetch: fetchWithToken,
});
./Component.jsx
import { refetch } from './http';
const Component = ({ settingsFetch }) => <AnotherComponent settingsFetch={settingsFetch} />);
const ConnectedComponent = refetch(
({
match: { params: { someId } },
}) => ({
settingsFetch: {
url: 'http://some-url/api/v1/foo'
}
})
)(Component)
export default ConnectedComponent;
How can I mock this function to return a mocked Promise as the response?
Update: It's getting close by doing the following:
jest.mock('../helpers/http', () => ({
refetch: () => jest.fn(
(ReactComponent) => (ReactComponent),
),
}));
Now the error reads:
Warning: Failed prop type: The prop `settingsFetch` is marked as required in `ConnectedComponent`, but its value is `undefined`.
Which means I will probably have to provide the mocked responses for the fetches in there somewhere.

Answer 1

Jest itself is in charge of the modules. So in the following example you will see that the module coming from '../http' can be mocked.
You can then overwrite the props of that module by first adding the default props, and after that overwrite the ones you need with your own.
jest.mock('../http', () => {
return {
refetch: function(hocConf) {
return function(component) {
component.defaultProps = {
...component.defaultProps,
settingsFetch: {},
// remember to add a Promise instead of an empty object here
};
return component;
};
},
};
});