Enzyme cannot find child component in shallow test

Question

Is this not the correct way to render a react/reflux test with enzyme but without the store, ie, "dumb"

import React from 'react'
import { shallow, render } from 'enzyme'
import { Controls } from '../Controls' // named export
import LoadingSpinner from '../LoadingSpinner'
let wrapper
let loadingFlags = {
  controls: true
}
describe('<Controls />', () => {
  it('should render only the loading spinner', () => {
    wrapper = shallow(<Controls loadingFlags={loadingFlags} />) // this ensures the spinner will show until data is ready
    expect(wrapper.length).toEqual(1) // test passes
    expect(wrapper.find(LoadingSpinner)).to.have.length(1)
    // ^ TypeError: Cannot read property 'have' of undefined
  })
})

When I log wrapper.html() I can see the <img class='spinner' /> is rendered, but enzyme cannot find it as a component. To me, the docs indicate this is exactly what I should be doing. I suppose I could check for a child with that class, but that seems messier than checking for the component itself, eg the class changes within the Spinner component.

How can I test for the existence of this child component?

What are you using as the test runner? It looks like the test runner you're using does not accept the `.to.have` syntax — Grandas, Sep 01 '17 at 00:25

score 7 · Answer 1 · answered Sep 01 '17 at 10:05

The test will work fine with shallow, but the assertion has a TypeError because it doesn't exist - it looks like you are using Jest, but the enzyme docs show assertions using chai BDD library.

Use the Jest equivalent instead:

expect(wrapper.find(LoadingSpinner)).toHaveLength(1)

panghea · Answer 2 · 2017-09-01T08:11:18.880

You should use a mount().

from https://github.com/airbnb/enzyme/blob/master/docs/guides/jsdom.md

import test from 'ava';
import React from 'react';
import { mount, shallow, render } from 'enzyme'

import LoadingSpinner, {Controls} from './LoadingSpinner';
// jsdom init start
const { JSDOM } = require('jsdom');

const jsdom = new JSDOM('<!doctype html><html><body></body></html>');
const { window } = jsdom;

function copyProps(src, target) {
    const props = Object.getOwnPropertyNames(src)
        .filter(prop => typeof target[prop] === 'undefined')
        .map(prop => Object.getOwnPropertyDescriptor(src, prop));
    Object.defineProperties(target, props);
}

global.window = window;
global.document = window.document;
global.navigator = {
    userAgent: 'node.js',
};
copyProps(window, global);
// jsdom init end

test('<Controls />' , t => {
    let wrapper = shallow(<Controls />);
    let mntWrapper = mount(<Controls />);
    t.true(wrapper.length == 1);
    t.true(wrapper.find(LoadingSpinner).length === 1);

    t.true(mntWrapper.find("img").length === 1);
    t.true(mntWrapper.render().find('img').length === 1);
    // if you need to test attributes check below.
    t.true(mntWrapper.render().find('img')[0].attribs.src.indexOf('foo') >= 0);
});

Enzyme cannot find child component in shallow test

How can I test for the existence of this child component?

2 Answers2