fetch-mock-jest

fetch-mock-jest

Wrapper around fetch-mock - a comprehensive, isomorphic mock for the fetch api - which provides an interface that is more idiomatic when working in jest

Installation

npm install -D fetch-mock-jest

global fetch

const fetchMock = require('fetch-mock-jest')

node-fetch

jest.mock('node-fetch', () => require('fetch-mock-jest').sandbox())
const fetchMock = require('node-fetch')

API

All the built in jest function inspection assertions can be used, e.g. expect(fetchMock).toHaveBeenCalledWith('http://example.com').

fetch.mockClear() can be used to reset the call history

fetch.mockReset() can be used to remove all configured mocks

All other jest methods for configuring mock functions are disabled as fetch-mock's own methods should always be used

fetchMock.mock.calls and fetchMock.mock.results are also exposed, giving access to manually inspect the calls.

The following custom jest expectation methods, proxying through to fetch-mock's inspection methods are also available. They can all be prefixed with the .not helper for negative assertions.

• expect(fetchMock).toHaveFetched(filter, options)
• expect(fetchMock).toHaveLastFetched(filter, options)
• expect(fetchMock).toHaveNthFetched(n, filter, options)
• expect(fetchMock).toHaveFetchedTimes(n, filter, options)
• expect(fetchMock).toBeDone(filter)

filter and options are the same as those used by fetch-mock's inspection methods

TODO

These would also be useful jest extensions:

• toHaveFetched
• toHaveRespondedWith(object | status | string ) (using fetch-mock internals to convert to a response config, then use jest objectMatching)