Test React Component using Redux and react-testing-library

Question

I am new to testing redux connected components in React and trying to figure out how to test them.

Currently I'm using react-testing-library and having trouble setting up the my renderWithRedux function to correctly setup redux.

Here is a sample component:

import React, { Component } from 'react'
import { connect } from 'react-redux'

class Sample extends Component {

    constructor(props) {
        super(props);
        this.state = {
           ...
        }
    }

    componentDidMount() {
        //do stuff
        console.log(this.props)
    }


    render() {

        const { user } = this.props

        return(
            <div className="sample">
                {user.name}
            </div>
        )

    }

}

const mapStateToProps = state => ({
    user: state.user
})

export default connect(mapStateToProps, {})(Sample);

Here is a sample test:

import React from 'react';
import { createStore } from 'redux'
import { Provider } from 'react-redux'
import { render, cleanup } from 'react-testing-library';
import Sample from '../components/sample/'

const user = {
    id: 1,
    name: "John Smith"
}}

function reducer(state = user, action) {
    //dont need any actions at the moment
    switch (action.type) {
      default:
        return state
    }
}

function renderWithRedux(
    ui,
    { initialState, store = createStore(reducer, initialState) } = {}
    ) {
    return {
        ...render(<Provider store={store}>{ui}</Provider>),
        store,
    }
}

afterEach(cleanup)

test('<Sample> example text', () => {
    const { getByTestId, getByLabelText } = renderWithRedux(<Sample />)
    expect(getByText(user.name))
})  

The user prop value always results as undefined. I have re-written this a couple of ways but can't seem to get it to work. If I pass the user data directly as a prop to Sample component in the test, it still resolves to be undefined.

I am learning from the tutorials and examples via the offical docs, like this one: https://github.com/kentcdodds/react-testing-library/blob/master/examples/tests/react-redux.js

Any pointers, tips or solutions would be greatly appreciated!

Answer 1

You should wrap the component inside Provider, here is the simple example

import React from 'react';
import { render } from '@testing-library/react';
import '@testing-library/jest-dom';
import { Provider } from "react-redux";
import configureMockStore from "redux-mock-store";

import TestedComponent from '../index';

const mockStore = configureMockStore();
const store = mockStore({});

const renderTestedComponent = () => {
  return render(
    <Provider store={store}>
      <TestedComponent />
    </Provider>
  );
};

describe('test TestedComponent components', () => {
  it('should be render the component correctly', () => {
    const { container } = renderTestedComponent();

    expect(container).toBeInTheDocument();
  });
});