Enzyme: Shallow render new Context API

Created on 7 May 2019 · 1Comment · Source: enzymejs/enzyme

Current behavior

context.js: This file just creates the context with the new Context API.

import { createContext } from 'react'

const Context = createContext({})

export { Context }

provider.js: This is a wrapper that meant to declare the elements that should be passed to the context.

import { Context } from './context'
import PropTypes from 'prop-types'
import React, { Component } from 'react'

class Provider extends Component {

  constructor(props) {
    super(props)
  }

  getContext(props) {
    return Object.assign({}, {
      a: 1,
      b: 2,
      c: 3
    })
  }

  render() {
    return (
      <Context.Provider value={this.getContext(this.props)}>
        {this.props.children}
      </Context.Provider>
    )
  }

}

Provider.propTypes = {
  children: PropTypes.node
}

export default Provider

dummy.js: This component uses the context.

import { Context } from '~/utils/context'
import React, { Component } from 'react'

class Dummy extends Component {

  render() {
    const { a, b, c } = this.context

    return (
      <ul>
        <li>{a}</li>
        <li>{b}</li>
        <li>{c}</li>
      </ul>
    )
  }

}

Dummy.contextType = Context

export default Dummy

dummy.spec.js: This is the test that should run.

import Dummy from '../dummy'

const context = {
  a: 1,
  b: 2,
  c: 3
}

describe('dummy', () => {
    it('context should be defined', () => {
      const wrapper = shallow(<Dummy />, { context })
      expect(wrapper.context()).toEqual(context)
    })
})

This code works when running the app as i'm receiving the context. But when testing the context is just an empty object.

Note: When moving Dummy.contextType = Context to

Dummy.contextTypes = {
   a: PropTypes.number,
   ...
}

the context is correctly defined. But as i'm using the new API this is not possible. I also test with mount but with the same result. Also i tried to upgrade enzyme and the adapter to the latest version without success.

Expected behavior

The context should be declared on the component and in the test when running wrapper.context()

API

[x] shallow
[ ] mount
[ ] render

Version

| library | version
| ------------------- | -------
| enzyme | ^3.9.0
| react | ^16.8.2
| react-dom | ^16.8.2
| react-test-rendered | N/A
| adapter (below) |