Registry / testing / meiro-jest-fetch-mock

meiro-jest-fetch-mock

library3.0.4jsnpmunverified

Mock for fetch calls in Jest tests. v3.0.4 enables mocking global fetch (including cross-fetch polyfill) with Jest's built-in mock functions. It provides a simple API with mockResponse, mockResponses, mockReject, and mockOnce methods. Supports TypeScript types, conditional mocking by URL, and resetting state between tests. Lightweight alternative to MSW or nock for unit tests.

testing

npm install meiro-jest-fetch-mock

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · MEIRO-JEST-FETCH-M

meiro-jest-fetch-mock

testingjavascriptv3.0.4

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

enableMocks

✓ import { enableMocks } from 'jest-fetch-mock'

✗ import jestFetchMock from 'jest-fetch-mock'

enableMocks is a named export. Default import is not available.

fetchMock

✓ // After enableMocks(), fetchMock is available globally fetchMock.mockResponse('ok')

✗ import { fetchMock } from 'jest-fetch-mock'

fetchMock is not a named export; it becomes a global after calling enableMocks().

GlobalFetchMock

✓ import type { GlobalFetchMock } from 'jest-fetch-mock'

✗ import { GlobalFetchMock } from 'jest-fetch-mock'

GlobalFetchMock is a TypeScript type export, named import for type-only usage.

Setup with enableMocks() and basic mock/assert pattern using fetchMock.mockResponse and Jest matchers.

// setupJest.js (or similar setup file) require('jest-fetch-mock').enableMocks(); // yourComponent.test.js test('fetches data', async () => { fetchMock.mockResponse(JSON.stringify({ data: 'test' })); const response = await fetch('/api/data'); const json = await response.json(); expect(json.data).toBe('test'); expect(fetch).toHaveBeenCalledTimes(1); expect(fetch).toHaveBeenCalledWith('/api/data'); });

Debug

Known issues

breakingJest's resetMocks default changed to true in Jest 4.0.1 causing fetchMock to reset unexpectedly

fix

Set Jest config 'resetMocks: false' if using setup file to call enableMocks(), or call enableMocks() in beforeEach.

affects: >=3.0.0

gotchafetch is replaced globally by enableMocks — using real fetch after mock requires donMock()

fix

Call fetchMock.dontMock() after enableMocks() to default to real fetch, then doMock() per test.

affects: >=2.0.0

deprecatedmockResponseOnce and mockRejectOnce are deprecated in favor of mockOnce

fix

Use fetchMock.once().mockResponse(...) or fetchMock.once().mockReject(...) chain.

affects: >=3.0.0

gotchafetchMock is not available as an import — must call enableMocks() first

fix

Always call enableMocks() in setup file; then use global fetchMock variable.

affects: >=3.0.0

gotchamockResponses does not clear previous mock — can accumulate

fix

Call fetchMock.resetMocks() before using mockResponses in a test.

affects: >=2.0.0

Errors

Common errors & fixes

TypeError: fetchMock.mockResponse is not a function

enableMocks() was not called, so fetchMock global is undefined or not fully initialized.

fix

Ensure setupJest.js calls require('jest-fetch-mock').enableMocks() and Jest setupFiles config points to it.

Cannot find module 'jest-fetch-mock' from 'setupJest.js'

jest-fetch-mock is not installed or node_modules missing.

fix

Run npm install --save-dev jest-fetch-mock and ensure it's in devDependencies.

jest.fn() is not a function

Incorrect import or setup; jest not available in setup file.

fix

Ensure Jest is configured properly; setup file should be in setupFiles not setupFilesAfterFramework.

Upgrade

Version history

3.0.4latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/jefflau/jest-fetch-mock ↗

packagemeiro-jest-fetch-mock ↗

homepagehttps://github.com/jefflau/jest-fetch-mock#readme ↗