开玩笑：测试套件无法运行，意外令牌= [英] Jest: Test suite failed to run, Unexpected token =

问题描述

我正在尝试使用Jest / Enzyme测试React组件。我希望测试至少可以运行，但是在导入文件且未进入测试本身时它已经失败。所以我想知道我缺少什么配置？

I am trying to test a React component with Jest/Enzyme. I expect the test to at least run, but it already fails when it is importing files and does not get to the test itself. So I am wondering what in the configuration I am missing?

错误：

__tests__/Favorite.test.js
  ● Test suite failed to run

    /src/components/favorite/Favorite.js: Unexpected token (13:13)
        11 |   }
        12 |
      > 13 |   isFavorite = (props) => {
           |              ^
        14 |     return localStorage.getItem(props.recipe.id) ? true : false
        15 |   }
        16 |

测试文件：

import React from 'react'
import { mount } from 'enzyme'
import Favorite from '../src/components/favorite/Favorite'


describe('Favorite', () => {
  const recipe = {id: "12345"}
  const favorite = mount(<Favorite recipe={recipe}/>)
  // assertions
})

.babelrc：

{
  "presets": ["es2015", "react"]
}

package.json：

package.json:

"devDependencies": {
    "babel-jest": "^21.2.0",
    "babel-preset-es2015": "^6.24.1",
    "babel-preset-react": "^6.24.1",
    "enzyme": "^3.2.0",
    "enzyme-adapter-react-16": "^1.1.0",
    "enzyme-to-json": "^3.2.2",
    "jest": "^21.2.1",
    "react-test-renderer": "^16.1.1"
  },
  "jest": {
    "setupTestFrameworkScriptFile": "./src/setupTests.js",
    "moduleNameMapper": {
      "\\.(css|jpg|png|svg|ico)$": "<rootDir>/empty-module.js"
    }
  }

更新：

当我将功能声明从胖箭头更改为function关键字时，将运行测试。我想知道为什么？

When I change the declaration of the functions from fat arrow to function keyword, the tests run. I wonder why?

不适用于Jest的胖箭头功能：

Fat arrow function that does not work with Jest:

// Favorite.js

  isFavorite = (props) => {
    return localStorage.getItem(props.recipe.id) ? true : false
  }

与Jest兼容的功能关键字：

Function keyword that does work with Jest:

// Favorite.js

  isFavorite(props) {
    return localStorage.getItem(props.recipe.id) ? true : false
  }

推荐答案

您错过了 babel-preset-stage-0 软件包。

1. 添加它： 纱线添加babel-preset-stage-0 --dev

编辑您的 .babelrc ： { presets：[ es2015， react， babel-preset-stage-0]}

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