Unit Test Vue + Webpack + Karma + Jasmine

.babelrc

{
    "presets": [
        [
            "env",
            {
                "modules": false,
                "targets": {
                    "browsers": [
                        "> 1%",
                        "last 2 versions",
                        "not ie <= 8"
                    ]
                }
            }
        ],
        "stage-2"
    ],
    "plugins": [
        "transform-runtime"
    ],
    "env": {
        "test": {
            "presets": [
                "env",
                "stage-2"
            ],
            "plugins": [
                [
                    "istanbul",
                    {
                        "exclude": [
                            "**/tests/**/*.js"
                        ]
                    }
                ]
            ]
        }
    }
}

index.js

// tests/index.js
import Vue from 'vue'

Vue.config.productionTip = false

// require all modules ending in "Spec" from the
// current directory and all subdirectories
const testsContext = require.context(".", true, /Spec$/);
testsContext.keys().forEach(testsContext);

// requires all components
const componentContext = require.context("../components/", true);
componentContext.keys().forEach(componentContext);

const storeContext = require.context("../store/", true);
storeContext.keys().forEach(storeContext);

karma.conf.js

const webpack = require('webpack')
const path = require('path')

const jsDir = 'resources/assets/js/'
const outputDir = path.resolve(__dirname, 'build/logs')

module.exports = function (config) {
  config.set({
    basePath: jsDir,
    // to run in additional browsers:
    // 1. install corresponding karma launcher
    //    http://karma-runner.github.io/0.13/config/browsers.html
    // 2. add it to the `browsers` array below.
    browsers: ['PhantomJS'],
    frameworks: ['jasmine', 'phantomjs-shim'],
    reporters: ['spec', 'coverage', 'junit'],
    files: [
      // https://github.com/vuejs-templates/webpack/issues/474
      path.resolve(__dirname, 'node_modules/es6-promise/dist/es6-promise.auto.js'),
      'tests/index.js'
    ],
    exclude: [

    ],
    preprocessors: {
      './tests/index.js': ['webpack', 'sourcemap']
    },
    webpack: {
      // karma watches the test entry points
      // (you don't need to specify the entry option)
      devtool: '#inline-source-map',
      module: {
        loaders: [
          {
            test: /\.js$/,
            loader: 'babel-loader',
            exclude: /node_modules/
          },
          {
            test: /\.vue$/,
            loader: 'vue-loader'
          }
        ]
      },
      resolve: {
        extensions: ['.js'],
        alias: {
          components: path.resolve(__dirname, jsDir + 'components/'),
          store: path.resolve(__dirname, jsDir + 'store/')
        }
      },
      plugins: [
        new webpack.DefinePlugin({
          'process.env': {
            NODE_ENV: '"testing"'
          }
        })
      ]
    },
    webpackMiddleware: {
      noInfo: true
    },
    junitReporter: {
      outputFile: outputDir + '/karma-junit.xml',
      suite: 'JS Unit Tests'
    },
    coverageReporter: {
      // includeAllSources: true,
      dir: path.resolve(__dirname, outputDir + '/coverage'),
      reporters: [
        { type: 'lcov', subdir: 'lcov' },
        { type: 'cobertura', subdir: 'cobertura' },
        { type: 'text-summary' }
      ]
    }
  })
}

package.json

{
    "scripts": {
        "unit": "cross-env BABEL_ENV=test karma start karma.conf.js --single-run",
        "watch-unit": "cross-env BABEL_ENV=test karma start karma.conf.js --auto-watch"
    },
    "devDependencies": {
        "babel-plugin-istanbul": "^4.1.4",
        "babel-plugin-transform-runtime": "^6.23.0",
        "babel-preset-es2015": "^6.24.1",
        "babel-preset-stage-2": "^6.24.1",
        "cross-env": "^5.0.5",
        "jasmine-core": "^2.7.0",
        "karma": "^1.7.0",
        "karma-babel-preprocessor": "^6.0.1",
        "karma-cli": "^1.0.1",
        "karma-coverage": "^1.1.1",
        "karma-jasmine": "^1.1.0",
        "karma-junit-reporter": "^1.2.0",
        "karma-phantomjs-launcher": "^1.0.4",
        "karma-phantomjs-shim": "^1.4.0",
        "karma-sourcemap-loader": "^0.3.7",
        "karma-spec-reporter": "^0.0.31",
        "karma-webpack": "^2.0.4",
        "phantomjs-prebuilt": "^2.1.15",
        "vue-loader": "^13.0.4",
        "vue-style-loader": "^3.0.1",
        "vue-template-compiler": "^2.4.2"
    },
    "dependencies": {
        "vue": "^2.4.2
    },
    "browserslist": [
        "> 1%",
        "last 2 versions",
        "not ie <= 8"
    ]
}