Test asynchronous nested component - reactjs

Question

Say I have the following wrapper component:
'use strict'
import React, {PropTypes, PureComponent} from 'react'
import {update} from '../../actions/actions'
import LoadFromServerButton from '../LoadFromServerButton'
import {connect} from 'react-redux'
export class FooDisplay extends PureComponent {
render () {
return (
<p>
<span className='foo'>
{this.props.foo}
</span>
<LoadFromServerButton updateFunc={this.props.update} />
</p>
)
}
}
export const mapStateToProps = (state) => {
return {foo: state.foo.foo}
}
FooDisplay.propTypes = {
foo: PropTypes.string
}
export const mapDispatchToProps = (dispatch) => {
return {
update: (foo) => dispatch(update(foo))
}
}
export default connect(mapStateToProps, mapDispatchToProps)(FooDisplay)
and the following inner component:
'use strict'
import React, {PropTypes, PureComponent} from 'react'
import {get} from '../../actions/actions'
import ActiveButton from '../ActiveButton'
import {connect} from 'react-redux'
export class LoadFromServerButton extends PureComponent {
doUpdate () {
return this.props.get().then(this.props.updateFunc)
}
render () {
return (
<ActiveButton action={this.doUpdate.bind(this)} actionArguments={[this.props.foo]} text='fetch serverside address' />
)
}
}
export const mapStateToProps = (state) => {
return {foo: state.foo.foo}
}
export const mapDispatchToProps = (dispatch) => {
return {
get: () => dispatch(get())
}
}
LoadAddressFromServerButton.propTypes = {
updateFunc: PropTypes.func.isRequired
}
export default connect(mapStateToProps, mapDispatchToProps)(LoadFromServerButton)
ActiveButton is a very thin wrapper around a button with an onclick and arguments destructuring.
Now lets say that I my get action is written as follows:
export const get = () => dispatch => http('/dummy_route')
.spread((response, body) => dispatch(actOnThing(update, body)))
Now if I write a test like so:
/* global window, test, expect, beforeAll, afterAll, describe */
'use strict'
import React from 'react'
import FooDisplay from './index'
import {mount} from 'enzyme'
import {Provider} from 'react-redux'
import configureStore from '../../store/configureStore'
import nock, {uriString} from '../../config/nock'
import _ from 'lodash'
const env = _.cloneDeep(process.env)
describe('the component behaves correctly when integrating with store and reducers/http', () => {
beforeAll(() => {
nock.disableNetConnect()
process.env.API_URL = uriString
})
afterAll(() => {
process.env = _.cloneDeep(env)
nock.enableNetConnect()
nock.cleanAll()
})
test('when deep rendering, the load event populates the input correctly', () => {
const store = configureStore({
address: {
address: 'foo'
}
})
const display = mount(<Provider store={store}><FooDisplay /></Provider>,
{attachTo: document.getElementById('root')})
expect(display.find('p').find('.address').text()).toEqual('foo')
const button = display.find('LoadFromServerButton')
expect(button.text()).toEqual('fetch serverside address')
nock.get('/dummy_address').reply(200, {address: 'new address'})
button.simulate('click')
})
})
This results in:
Unhandled rejection Error: Error: connect ECONNREFUSED 127.0.0.1:8080
After a little bit of thinking, this is due to the fact that the test does not return a promise, as the button click causes the promise to fire under the hood, therefore, afterAll runs immediatly, cleans nock, and a real http connection goes over the wire.
How do I test this case? I don't seem to have an easy way to return the correct promise... How do I test updates to the DOM resulting from these updates?

Answer 1

In order to mock only one method of the imported module, use .requireActual(...)
jest.mock('../your_module', () => ({
...(jest.requireActual('../your_module')),
YourMethodName: () => { return { type: 'MOCKED_ACTION'}; }
}));

Answer 2

As you mentioned the problem is that you dont have the promise to return from test. So to make get return a know promise you can just mock get directly without using nock:
import {get} from '../../actions/actions'
jest.mock('../../actions/actions', () => ({get: jest.fn}))
this will replace the action module with an object {get: jestSpy}
in your test you can then create a promise and let get return this and also return this promise from your test:
it('', ()=>{
const p = new Promise.resolve('success')
get.mockImplementation(() => p)//let get return the resolved promise
//test you suff
return p
})