I was trying to implement the example shown in Jest website: Getting started with Jest.

While running npm test on I was getting the following error:

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 and sum.test.js are an exact copy of the example shown in Getting started with Jest.

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

  }

}

So, how can I get rid of TypeError: environment.setup is not a function error?