If you're using NextJs, you probably want to test getInitialProps
on your pages. You can call it from your un-instantiated imported class, and use the props it returns to instantiate an Enzyme wrapper. Here's a nice little pattern:
import { shallow } from 'enzyme'
import MyPage from '../components/my-page'
describe('My Page', () => {
var wrapper
beforeEach(async () => {
const props = await MyPage.getInitialProps()
wrapper = shallow(<MyPage {...props} />)
})
})