Mock a cross-fetch ponyfill #122
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I use unfetch and I was able to get everything working with this setup file: import { GlobalWithFetchMock } from 'jest-fetch-mock';
const customGlobal = global as GlobalWithFetchMock;
customGlobal.fetch = require('jest-fetch-mock');
customGlobal.fetchMock = customGlobal.fetch;
jest.setMock('unfetch', fetch); // Use this to mock your ponyfilled fetch moduleHope this helps! |
export const mockedFetch = jest.fn() as jest.MockedFunction<typeof fetch>;
jest.mock("cross-fetch", () => ({
...jest.requireActual("cross-fetch"),
__esModule: true,
fetch: mockedFetch,
default: mockedFetch,
}));
// must come AFTER mocking!
import fetch, { Response } from "cross-fetch";
export function mockFetchOnce(status: number, json: unknown): void {
mockedFetch.mockResolvedValueOnce(new Response(JSON.stringify(json), { status }));
} |
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I managed to do it by simply doing this in the setup test file: import fetchMock from "jest-fetch-mock";
jest.setMock("cross-fetch", fetchMock);You can look at the complete PR where I introduced |
ryanrhee
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that referenced
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Jan 26, 2022
resolves jefflau#122 From jefflau#122 (comment)
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This is the recommended way according to jest documentation: jest.mock('cross-fetch', () => {
const fetchMock = require('jest-fetch-mock');
// Require the original module to not be mocked...
const originalFetch = jest.requireActual('cross-fetch');
return {
__esModule: true,
...originalFetch,
default: fetchMock
};
});
import fetch from 'cross-fetch';
//Do not mock unless we explicitly request it.
fetch.dontMock();
describe('fetch', () => {
test('fetch', async () => {
fetch.mockResponse(JSON.stringify({ hello: 'world' }));
//Activate the mock
//This will not result into a query to google:
fetch.doMock();
expect(await (await fetch('https://www.google.com')).json()).toEqual({
hello: 'world'
});
//Turn off
fetch.dontMock();
//Now you can fetch() stuff and the mock won't be applied.
//This will really query google.com:
expect((await fetch('https://www.google.com')).status).toEqual(200);
});
}); |
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I'm currently testing a project, which uses cross-fetch ponyfills in the files (i.e.
import fetch from "cross-fetch").this comment in #82 suggests just using cross-fetch as polyfill instead of ponyfill, but that's not an option in my case.
Is it possible to mock the fetch imported as a module?
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