Test setup

.babelrc

{
  "presets": [
    "es2015",
    "stage-2"
  ]
}

index.js

export const identity = (x) => x;
export const square = (x) => x * x;

mocha.opts

--compilers js:babel-register
test.js

package.json

{
  "name": "lib.js",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "mocha --opts mocha.opts",
    "test:watch": "mocha --opts mocha.opts --watch --reporter min"
  },
  "author": "Justin Obney",
  "license": "MIT",
  "devDependencies": {
    "babel-preset-es2015": "^6.3.13",
    "babel-preset-stage-2": "^6.3.13",
    "babel-register": "^6.3.13",
    "expect": "^1.13.4",
  }
}

test.js

import expect from 'expect';
import {identity, square} from './index';

describe('setup', () => {
  it('works', () => {
    expect(identity(5)).toBe(5);
    expect(square(5)).toBe(25);
  });
});