How to Unit Test React-Redux Connected Components?

Question

I am using Mocha, Chai, Karma, Sinon, Webpack for Unit tests.

I followed this link to configure my testing environment for React-Redux Code.

How to implement testing + code coverage on React with Karma, Babel, and Webpack

I can successfully test my action and reducers javascript code, but when it comes to testing my components it always throw some error.

import React from 'react';
import TestUtils from 'react/lib/ReactTestUtils'; //I like using the Test Utils, but you can just use the DOM API instead.
import chai from 'chai';
// import sinon from 'sinon';
import spies from 'chai-spies';

chai.use(spies);

let should = chai.should()
  , expect = chai.expect;

import { PhoneVerification } from '../PhoneVerification';

let fakeStore = {
      'isFetching': false,
      'usernameSettings': {
        'errors': {},
        'username': 'sahil',
        'isEditable': false
      },
      'emailSettings': {
        'email': '[email protected]',
        'isEmailVerified': false,
        'isEditable': false
      },
      'passwordSettings': {
        'errors': {},
        'password': 'showsomestarz',
        'isEditable': false
      },
      'phoneSettings': {
        'isEditable': false,
        'errors': {},
        'otp': null,
        'isOTPSent': false,
        'isOTPReSent': false,
        'isShowMissedCallNumber': false,
        'isShowMissedCallVerificationLink': false,
        'missedCallNumber': null,
        'timeLeftToVerify': null,
        '_verifiedNumber': null,
        'timers': [],
        'phone': '',
        'isPhoneVerified': false
      }
}

function setup () {
    console.log(PhoneVerification);
    // PhoneVerification.componentDidMount = chai.spy();
    let output = TestUtils.renderIntoDocument(<PhoneVerification {...fakeStore}/>);
    return {
        output
    }
}

describe('PhoneVerificationComponent', () => {
    it('should render properly', (done) => {
        const { output } = setup();
        expect(PhoneVerification.prototype.componentDidMount).to.have.been.called;
        done();
    })
});

This following error comes up with above code.

FAILED TESTS:
  PhoneVerificationComponent
    ✖ should render properly
      Chrome 48.0.2564 (Mac OS X 10.11.3)
    Error: Invariant Violation: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined.

Tried switching from sinon spies to chai-spies.

How should I unit test my React-Redux Connected Components(Smart Components)?

Answer 1

A prettier way to do this, is to export both your plain component, and the component wrapped in connect. The named export would be the component, the default is the wrapped component:

export class Sample extends Component {

    render() {
        let { verification } = this.props;
        return (
            <h3>This is my awesome component.</h3>
        );
    }

}

const select = (state) => {
    return {
        verification: state.verification
    }
}

export default connect(select)(Sample);

In this way you can import normally in your app, but when it comes to testing you can import your named export using import { Sample } from 'component'.