MWE re. karma-browserify#137

README.md

Run npm install then gulp && karma start to try out the tests.

gulpfile.js

gulp = require('gulp')
browserify = require('browserify')
source = require('vinyl-source-stream')

gulp.task('default', function () {
  var bify = browserify({
    entries: './source.js',
    debug: true
  })
    .transform(require('babelify'))
    .bundle()
    .pipe(source("./dest.js"))
    .pipe(gulp.dest('./'))
})

karma.conf.js

module.exports = function(config) {
  config.set({
    basePath: '',
    frameworks: ['mocha', 'chai'],
    files: [ 'dest.js' ],
    exclude: [ ],
    preprocessors: { },
    reporters: ['progress'],
    port: 9876,
    colors: true,
    logLevel: config.LOG_INFO,
    autoWatch: true,
    browsers: ['Chrome'],
    singleRun: false
  })
}

package.json

{
  "name": "karma-issue-1495",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "babelify": "^6.1.3",
    "browserify": "^11.0.0",
    "chai": "^3.2.0",
    "gulp": "^3.9.0",
    "karma": "^0.13.3",
    "karma-browserify": "^4.2.1",
    "karma-chai": "^0.1.0",
    "karma-chrome-launcher": "^0.2.0",
    "karma-mocha": "^0.2.0",
    "vinyl-source-stream": "^1.1.0"
  },
  "devDependencies": {
    "karma-mocha": "^0.2.0",
    "mocha": "^2.2.5"
  }
}

source.js

// A file in es6
//
class Foo {
  constructor() { }

  boo() {
    chai.assert.equal("The line is", "7?")
  }
}

describe('test', function () {
  it("fails", function () {
    new Foo().boo()
  })
  it("throws", function () {
    throw new Error("Error on Line 16")
  })
})