• Introduction
• Quickstart
• Installation and usage
• API documentation
• Troubleshooting
• Examples

Troubleshooting

fetch is assigned to a local variable, not a global

First of all, consider whether you could just use fetch as a global. Here are 3 reasons why this is a good idea:

• The fetch standard defines it as a global (and in some cases it won’t work unless bound to window), so to write isomorphic code it’s probably best to stick to this pattern
• isomorphic-fetch takes care of installing it as a global in nodejs or the browser, so there’s no effort on your part to do so.
• fetch-mock is primarily designed to work with fetch as a global and your experience of using it will be far more straightforward if you follow this pattern

Still not convinced?

In that case fetchMock.sandbox() can be used to generate a function which you can pass in to a mock loading library such as mockery instead of fetch

fetch doesn’t seem to be getting mocked?

• If using a mock loading library such as mockery, are you requiring the module you’re testing after registering fetch-mock with the mock loader? You probably should be (Example incorrect usage). If you’re using ES6 import it may not be possible to do this without reverting to using require() sometimes.
• If using isomorphic-fetch in your source, are you assigning it to a fetch variable? You shouldn’t be i.e.
  • import 'isomorphic-fetch', not import fetch from 'isomorphic-fetch'
  • require('isomorphic-fetch'), not const fetch = require('isomorphic-fetch')

Environment doesn’t support requiring fetch-mock?

• If your client-side code or tests do not use a loader that respects the browser field of package.json use require('fetch-mock/es5/client').
• If you need to use fetch-mock without commonjs, you can include the precompiled node_modules/fetch-mock/es5/client-browserified.js in a script tag. This loads fetch-mock into the fetchMock global variable.
• For server side tests running in nodejs 0.12 or lower use require('fetch-mock/es5/server')

Matching Request objects in node fails

In node, if using npm at a version less than 2 the Request constructor used by fetch-mock won’t necessarily be the same as the one used by node-fetch. To fix this either:

• upgrade to [email protected]
• use fetchMock.config.Request = myRequest, where myRequest is a reference to the Request constructor used in your application code.