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Global or non-global

fetch can be used by your code globally or locally. It's important to determine which one applies to your codebase as it will impact how you use fetch-mock

Global fetch​

In the following scenarios fetch will be a global

  • When using native fetch (or a polyfill) in the browser
  • When node-fetch has been assigned to global in your Node.js process (a pattern sometimes used in isomorphic codebases)

By default fetch-mock assumes fetch is a global so no more setup is required once you've required fetch-mock.

Non-global fetch library​

In the following scenarios fetch will not be a global

  • Using node-fetch in Node.js without assigning to global
  • Using fetch-ponyfill in the browser
  • Using libraries which use fetch-ponyfill internally
  • Some build setups result in a non-global fetch, though it may not always be obvious that this is the case

The sandbox() method returns a function that can be used as a drop-in replacement for fetch. Pass this into your mocking library of choice. The function returned by sandbox() has all the methods of fetch-mock exposed on it, e.g.

const fetchMock = require('fetch-mock');
const myMock = fetchMock.sandbox().mock('/home', 200);
// pass myMock in to your application code, instead of fetch, run it, then...
expect(myMock.called('/home')).to.be.true;