setState value used in componentDidMount is not reflected in Enzyme test

user_2628355 0
Viewed 7913

Component.js

import React from 'react'
import request from 'superagent'

export default React.createClass({
    getInitialState() {
        return {cats: []}
    },

    componentDidMount() {
        request('/api', (err, res) => {
            if (err) return;
            this.setState({
                cats: res.body.results
            })
        })
    },

    render() {
        let cats = this.state.cats
        let catsList = (
            <ul>
                {cats.map((c) => <li key={c.id}>cat</li>)}
            </ul>
        )
        return (
            <div>
                {cats.length ? catsList : null}
            </div>
        )
    }
})

Component.test.js

jest.unmock('../app.js')
jest.unmock('superagent')

import React from 'react'
import {mount} from 'enzyme'
import nock from 'nock'
import App from '../app.js'

describe('App', () => {
    let ajaxFn
    beforeEach(() => {
        ajaxFn = nock('http://localhost')
            .get('/api')
            .reply(200, {
                results: [{id: 1}, {id: 2}, {id: 3}]
            })
    })

    it('renders correct number of cats', () => {
        let wrapper = mount(<App />)
        expect(wrapper.state('cats').length).toBe(3)
    })
})

The test does not pass. wrapper.state('cats').length is always 0.

I understand that setState doesn't guarantee to update state immediately, however if I log 'cats' in the component, I can see it updating.

enzyme jestjs reactjs
3 Answers

I am not familiar with all the libraries you are using, but since your code is being executed asynchronously the test is finishing before the state can be updated. I was able to solve this problem by adding async/await to the test:

it('renders correct number of cats', async () => {
    let wrapper = await mount(<App />)
    expect(wrapper.state('cats').length).toBe(3)
})
user_59559110
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