.spy(matcher)

Records call history while passing each call on to fetch to be handled by the network. Optionally pass in a matcher to scope this to only matched calls, e.g. to fetch a specific resource from the network.

To use .spy() on a sandboxed fetchMock, fetchMock.config.fetch must be set to the same fetch implementation used in your application. See how to configure this. By default this will be the locally installed version of node-fetch