fetch-error-jest-test.js

pit('calls request and failure actions if the fetch response was not successful', () => {

  window.fetch = jest.fn().mockImplementation(() => Promise.resolve(mockResponse(
    400, 'Test Error', '{"status":400, "statusText": Test Error!}')));

  return store.dispatch(fetchData(1234))
    .then(() => {
      const expectedActions = store.getActions();
      expect(expectedActions.length).toBe(2);
      expect(expectedActions[0]).toEqual({type: types.FETCH_DATA_REQUEST});
      expect(expectedActions[1]).toEqual({type: types.FETCH_DATA_FAILURE,
        error: {status: 400, statusText: 'Test Error'}});
    })
});

store is never defined here...

where does 'window' comes from?