I have a test file like so: (I am using create-react-app)

import React from 'react';

import ReactDOM from 'react-dom';

import App from './components/Calculator';



import { getAction, getResult } from './actions/'



import {shallow} from 'enzyme';

import toJson from 'enzyme-to-json';



import Enzyme from 'enzyme';

import Adapter from 'enzyme-adapter-react-16';



Enzyme.configure({ adapter: new Adapter() });



it('renders without crashing', () => {

  const wrapper = shallow(<App />)

  expect(toJson(wrapper)).toMatchSnapshot();

});



it('displays the choosen operator', () => {

  const action = {

      type: 'GET_ACTION',

      operator: '+'

    };

  expect(getAction("+")).toEqual(action)

})



it('displays the typed digit', () => {

  const action = {

    type: 'GET_RESULT',

    n: 3

  };

  expect(getResult(3)).toEqual(action);

})



it('checks that the clickevent for getNumber is called',() => {

  const clickEvent = jest.fn();

  const p = shallow(<p data-n="1" onClick={clickEvent}>1</p>)

  p.simulate('click')

  expect(clickEvent).toBeCalled();

})

and a package.json:

{

  "name": "my-app",

  "version": "0.1.0",

  "private": true,

  "dependencies": {

    "react": "^16.2.0",

    "react-dom": "^16.2.0",

    "react-scripts": "1.1.1"

  },

  "scripts": {

    "start": "react-scripts start",

    "build": "react-scripts build",

    // "test": "react-scripts test --env=jsdom",

    "test": "jest",

    "eject": "react-scripts eject"

  },

  "devDependencies": {

    "enzyme": "^3.3.0",

    "enzyme-adapter-react-16": "^1.1.1",

    "enzyme-to-json": "^3.3.3",

    "jest": "^22.4.3"

  }

}

when I run jest --updateSnapshot I get:

command not found: jest

but jest is installed.