mock.calls is undefined in jest test

I’m trying to test a React component by verifying that changeWindow gets called when I click a button. However, when I run the test, changeWindow.mock.calls is undefined. I can’t figure out what I’m missing—changeWindow is defined in the test as a function and changeWindow.mock is defined as [Object object]. Any ideas?

jest.mock('../../../../../../lib/util/changeWindow');
const changeWindow = require('../../../../../../lib/util/changeWindow').default;

describe('CardPage', () => {

    it('calls changeWindowLocation() on clicking button', () => {
        const onChangeMock = jest.fn();
        const component = enzyme.shallow(<CardPage status={'welcome'} onChange={onChangeMock}/>);
        component.find(Button).at(2).simulate('click');
        expect(changeWindow.mock.calls[0][0]).toEqual('/items/');
    });
});