How to test a component using react-redux hooks?

Question

I have a simple Todo component that utilizes react-redux hooks that I'm testing using enzyme but I'm getting either an error or an empty object with a shallow render as noted below.

What is the correct way to test components using hooks from react-redux?

Todos.js

const Todos = () => {
  const { todos } = useSelector(state => state);

  return (
    <ul>
      {todos.map(todo => (
        <li key={todo.id}>{todo.title}</li>
      ))}
    </ul>
  );
};

Todos.test.js v1

...

it('renders without crashing', () => {
  const wrapper = shallow(<Todos />);
  expect(wrapper).toMatchSnapshot();
});

it('should render a ul', () => {
  const wrapper = shallow(<Todos />);
  expect(wrapper.find('ul').length).toBe(1);
});

v1 Error:

...
Invariant Violation: could not find react-redux context value; 
please ensure the component is wrapped in a <Provider>
...

Todos.test.js v2

...
// imported Provider from react-redux 

it('renders without crashing', () => {
  const wrapper = shallow(
    <Provider store={store}>
      <Todos />
    </Provider>,
  );
  expect(wrapper).toMatchSnapshot();
});

it('should render a ul', () => {
  const wrapper = shallow(<Provider store={store}><Todos /></Provider>);
  expect(wrapper.find('ul').length).toBe(1);
});

v2 tests also fail since wrapper is the <Provider> and calling dive() on wrapper will return the same error as v1.

Thanks in advance for your help!

Answer 1

I could test a component which uses redux hooks using enzyme mount facility and providing a mocked store to the Provider:

Component

import React from 'react';
import AppRouter from './Router'
import { useDispatch, useSelector } from 'react-redux'
import StartupActions from './Redux/Startup'
import Startup from './Components/Startup'
import './App.css';

// This is the main component, it includes the router which manages
// routing to different views.
// This is also the right place to declare components which should be
// displayed everywhere, i.e. sockets, services,...
function App () {
  const dispatch = useDispatch()
  const startupComplete = useSelector(state => state.startup.complete)

  if (!startupComplete) {
    setTimeout(() => dispatch(StartupActions.startup()), 1000)
  }

  return (
    <div className="app">
      {startupComplete ? <AppRouter /> : <Startup />}
    </div>
  );
}

export default App;

Test

import React from 'react';
import {Provider} from 'react-redux'
import { mount, shallow } from 'enzyme'
import configureMockStore from 'redux-mock-store'
import thunk from 'redux-thunk';
import App from '../App';

const mockStore = configureMockStore([thunk]);

describe('App', () => {
  it('should render a startup component if startup is not complete', () => {
    const store = mockStore({
      startup: { complete: false }
    });
    const wrapper = mount(
      <Provider store={store}>
        <App />
      </Provider>
    )
    expect(wrapper.find('Startup').length).toEqual(1)
  })
})