React unit test with jest in es6

Question

I am pretty new in react world and trying to write simple friendslist application. I wrote my friends store in es6 style and using babel as transpiler from es5 to es6.

import AppDispatcher from '../dispatcher/app_dispatcher';
import { EventEmitter } from 'events';
import FRIENDS_CONST from '../constants/friends';

const CHANGE_EVENT = 'CHANGE';

let friendsList = [];


let add = (name) => {

    let counter = friendsList.length + 1;
    let newFriend = {
        id: counter,
        name: name
    };

    friendsList.push(newFriend);

}

let remove = (id) => {
    let index = friendsList.findIndex(e => e.id == id);
    delete friendsList[index];
}


let FriendsStore = Object.assign({}, EventEmitter.prototype, {

    getAll: () => {
        return friendsList;
    },

    emitChange: () => {
        this.emit(CHANGE_EVENT);
    },

    addChangeListener: (callback) => {
        this.on(CHANGE_EVENT, callback);
    },

    removeChangeListener: (callback) => {
        this.removeListener(CHANGE_EVENT, callback);
    }

});

AppDispatcher.register((action) => {

    switch (action.actionType) {
        case FRIENDS_CONST.ADD_FRIENDS:
            add(action.name);
            FriendsStore.emitChange();
            break;
        case FRIENDS_CONST.REMOVE_FRIENDS:
            remove(action.id);
            FriendsStore.emitChange();
            break;
    }

});

export default FriendsStore;

Now I want to test my store and wrote the unit test also in es6

jest.dontMock('../../constants/friends');
jest.dontMock('../friends_store');


describe('FriendsStore', () => {

    import FRIENDS from '../../constants/friends';
    import AppDispatcher from '../../dispatcher/AppDispatcher';
    import FriendsStore from '../friends_store';

    let FakeAppDispatcher;
    let FakeFriendsStore;
    let callback;

    let addFriends = {
        actionType: FRIENDS.ADD_FRIENDS,
        name: 'Many'
    };

    let removeFriend = {
        actionType: FRIENDS.REMOVE_FRIENDS,
        id: '3'
    };

    beforeEach(function() {
        FakeAppDispatcher = AppDispatcher;
        FakeFriendsStore = FriendsStore;
        callback = AppDispatcher.register.mock.calls[0][0];
    });

    it('Should initialize with no friends items', function() {
        var all = FriendsStore.getAll();
        expect(all).toEqual([]);
    });



}); 

When I execute the test with statement npm test, I've got the error message:

> [email protected] test /Volumes/Developer/reactjs/app5
> echo "Error: no test specified"

Error: no test specified

What am I doing wrong? The file structure looks as follow:

Answer 1

I did it following the tutorial:

npm install --save-dev jest babel-jest babel-preset-es2015 babel-preset-react react-test-renderer

then

add to package.json

  "scripts": {
    "test": "jest"
  },
  "jest": {
    "testPathDirs": [
      "src/main/resources/web_pages/__tests__"
    ]
  },

Result:

 PASS  src/main/resources/web_pages/__tests__/modules/utils/ValidationUtil.spec.js (5.214s)
  ✓ ValidateEmail (5ms)

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        6.092s, estimated 7s
Ran all test suites.

Answer 2

To test ES6 syntax and JSX files, they need to be transformed for Jest. Jest has a config variable where you can define a preprocessor (scriptPreprocessor). You can use the babel-jest preprocessor:

Make the following changes to package.json:

{
  "devDependencies": {
    "babel-jest": "*",
    "jest-cli": "*"
  },
  "scripts": {
    "test": "jest"
  },
  "jest": {
    "scriptPreprocessor": "<rootDir>/node_modules/babel-jest",
    "testFileExtensions": ["es6", "js"],
    "moduleFileExtensions": ["js", "json", "es6"]
  }
}

And run:

$ npm install