reactjs - 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

To mock useSelector use can do this

import * as redux from 'react-redux'

const spy = jest.spyOn(redux, 'useSelector')
spy.mockReturnValue({ username:'test' })