Mocking and spying

These methods allow mocking or spying on the fetch implementation used by your application.

fetchHandler

fetchMock.fetchHandler(url, requestInit)

A mock implementation of fetch.

By default it will error. In order to return responses .route(), .catch() and other routing methods of fetchMock must first be used to add routes to its internal router.

All calls made using fetchMock.fetchHandler are recorded in fetchMock.callHistory.

You can either pass fetchMock.fetchHandler into your choice of mocking library or use the methods below to mock global fetch.

mockGlobal()

Replaces globalThis.fetch with fm.fetchHandler

unmockGlobal()

Restores globalThis.fetch to its original state

spy(matcher, name)

Falls back to the fetch implementation set in fetchMock.config.fetch for a specific route (which can be named).

When no arguments are provided it will fallback to the native fetch implementation for all requests, similar to .catch().

spyGlobal()

Equivalent to calling .mockGlobal() followed by .spy()