我正在尝试实现Jest网站上显示的示例：Jest 入门。

在运行时npm test，出现以下错误：

FAIL  src/sum.test.js
  ● Test suite failed to run

    TypeError: environment.setup is not a function

      at node_modules/jest-runner/build/run_test.js:112:23

sum.js：

function sum(a, b){
  return a+b;
}
module.exports = sum;

sum.test.js：

const sum = require('./sum');

test('adding sum function', () => {
  expect(sum(234,4)).toBe(238);
})

sum.js并且sum.test.js是Jest入门中显示的示例的完整副本。

package.json：

{
  "name": "jest-demo-test",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "react": "^16.2.0",
    "react-dom": "^16.2.0",
    "react-scripts": "1.0.17"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "jest",
    "eject": "react-scripts eject"
  },
  "devDependencies": {
    "jest": "^22.0.4"
  }
}

那么，如何摆脱TypeError: environment.setup is not a function错误呢？