Диагностика повторяющихся отчетов о спецификациях с помощью Karma, Mocha и React 16.5

Пример.js

import React, {Component} from 'react'

export default class Example extends Component {
  render() {
    try {
      return (
        <div>{this.props.foo.bar}</div>
      )
    } catch(e) {
      console.log(e) // for logging purposes
      throw e
    }
  }
}

Пример.spec.js

import {expect} from 'chai'
import React from 'react'
import ReactDOM from 'react-dom'

class ExampleWrapper extends React.Component {
  constructor(props) {
    super(props)

    this.state = {
      error: false
    }
  }

  componentDidCatch(error) {
    console.log('there was a problem')
    this.setState({
      error: true
    })
  }

  render() {
    console.log('rendering!')
    if (this.state.error) {
      console.log('- rendering the error version')
      return <div>An error occurred during render</div>
    }

    console.log('- rendering the real version')
    return (
      <Example {...this.props} />
    )
  }
}

import Example from './Example'

describe('Example', () => {
  let $container

  beforeEach(() => {
    console.log('beforeEach')
    $container = document.createElement('div')
    document.body.appendChild($container)
  })

  afterEach(() => {
    console.log('afterEach')
    ReactDOM.unmountComponentAtNode($container)
    $container.remove()
  })

  async function mount(props) {
    return new Promise((resolve, reject) => {
      const done = () => {
        console.log('done rendering')
        resolve()
      }
      ReactDOM.render(<ExampleWrapper {...props} />, $container, done)
    })
  }

  it('fails this spec', async () => {
    console.log('start test 1')
    await mount({})
    expect(true).to.be.true
  })

  it('also fails, but because of the first spec', async () => {
    console.log('start test 2')
    await mount({foo: {}})
    expect(true).to.be.true
  })
})

Вывод спецификации ниже:

LOG LOG: 'beforeEach'
LOG LOG: 'start test 1'
LOG LOG: 'rendering!'
LOG LOG: '- rendering the real version'

  Example
    ✗ fails this spec
  Error: Uncaught TypeError: Cannot read property 'bar' of undefined (src/Example.spec.js:35380)
      at Object.invokeGuardedCallbackDev (src/Example.spec.js:16547:16)
      at invokeGuardedCallback (src/Example.spec.js:16600:31)
      at replayUnitOfWork (src/Example.spec.js:31930:5)
      at renderRoot (src/Example.spec.js:32733:11)
      at performWorkOnRoot (src/Example.spec.js:33572:7)
      at performWork (src/Example.spec.js:33480:7)
      at performSyncWork (src/Example.spec.js:33452:3)
      at requestWork (src/Example.spec.js:33340:5)
      at scheduleWork (src/Example.spec.js:33134:5)

ERROR LOG: 'The above error occurred in the <Example> component:
    in Example (created by ExampleWrapper)
    in ExampleWrapper

React will try to recreate this component tree from scratch using the error boundary you provided, ExampleWrapper.'
LOG LOG: 'there was a problem'
LOG LOG: 'done rendering'
LOG LOG: 'rendering!'
LOG LOG: '- rendering the error version'
LOG LOG: 'afterEach'
LOG LOG: 'beforeEach'
LOG LOG: 'start test 2'
LOG LOG: 'rendering!'
LOG LOG: '- rendering the real version'
LOG LOG: 'done rendering'
    ✓ also fails, but because of the first spec
    ✓ also fails, but because of the first spec
LOG LOG: 'afterEach'
LOG LOG: 'afterEach'

Chrome 69.0.3497 (Mac OS X 10.13.6): Executed 3 of 2 (1 FAILED) (0.014 secs / NaN secs)
TOTAL: 1 FAILED, 2 SUCCESS


1) fails this spec
     Example
     Error: Uncaught TypeError: Cannot read property 'bar' of undefined (src/Example.spec.js:35380)
    at Object.invokeGuardedCallbackDev (src/Example.spec.js:16547:16)
    at invokeGuardedCallback (src/Example.spec.js:16600:31)
    at replayUnitOfWork (src/Example.spec.js:31930:5)
    at renderRoot (src/Example.spec.js:32733:11)
    at performWorkOnRoot (src/Example.spec.js:33572:7)
    at performWork (src/Example.spec.js:33480:7)
    at performSyncWork (src/Example.spec.js:33452:3)
    at requestWork (src/Example.spec.js:33340:5)
    at scheduleWork (src/Example.spec.js:33134:5)

Что вызывает дублирование отчетов?

Почему это происходит в React 16+, а не в React 15?

Как я могу решить эту проблему?