feat: deprecate helper._

In preperation of upgrading to lodash@4 the internally exposed helper._ is deprecated.

Ref #1812

lib/file-list.js

@@ -14,11 +14,11 @@ var mm = require('minimatch')
 var Glob = require('glob').Glob
 var fs = Promise.promisifyAll(require('graceful-fs'))
 var pathLib = require('path')
+var _ = require('lodash')
 
 var File = require('./file')
 var Url = require('./url')
 var helper = require('./helper')
-var _ = helper._
 var log = require('./logger').create('watcher')
 
 // Constants

lib/file.js

@@ -6,7 +6,7 @@
 // Dependencies
 // ------------
 
-var _ = require('./helper')._
+var _ = require('lodash')
 
 // Constructor
 var File = function (path, mtime, doNotCache) {

lib/helper.js

@@ -167,4 +167,9 @@ exports.defer = function () {
 }
 
 // export lodash
-exports._ = _
+Object.defineProperty(exports, '_', {
+  get: function () {
+    console.log('DEPRECATED: use your own version of lodash, this will go away in karma@2.0')
+    return _
+  }
+})

lib/middleware/common.js

@@ -3,9 +3,9 @@
  */
 
 var mime = require('mime')
+var _ = require('lodash')
+
 var log = require('../logger').create('web-server')
-var helper = require('../helper')
-var _ = helper._
 
 var PromiseContainer = function () {
   var promise

lib/middleware/proxy.js

@@ -1,8 +1,8 @@
 var url = require('url')
 var httpProxy = require('http-proxy')
+var _ = require('lodash')
 
 var log = require('../logger').create('proxy')
-var _ = require('../helper')._
 
 var parseProxyConfig = function (proxies, config) {
   var endsWithSlash = function (str) {

lib/middleware/source_files.js

@@ -1,7 +1,8 @@
 var from = require('core-js/library/fn/array/from')
 var querystring = require('querystring')
+var _ = require('lodash')
+
 var common = require('./common')
-var _ = require('../helper')._
 var logger = require('../logger')
 var log = logger.create('middleware:source-files')
 

lib/reporter.js

@@ -1,11 +1,12 @@
 var util = require('util')
 var resolve = require('url').resolve
+var SourceMapConsumer = require('source-map').SourceMapConsumer
+var WeakMap = require('core-js/es6/weak-map')
+var _ = require('lodash')
+
 var log = require('./logger').create('reporter')
 var MultiReporter = require('./reporters/multi')
 var baseReporterDecoratorFactory = require('./reporters/base').decoratorFactory
-var SourceMapConsumer = require('source-map').SourceMapConsumer
-var WeakMap = require('core-js/es6/weak-map')
-var _ = require('./helper')._
 
 var createErrorFormatter = function (basePath, emitter, SourceMapConsumer) {
   var lastServedFiles = []

test/unit/file-list.spec.js

@@ -3,11 +3,11 @@ import {EventEmitter} from 'events'
 import mocks from 'mocks'
 import proxyquire from 'proxyquire'
 import pathLib from 'path'
-var helper = require('../../lib/helper')
-var _ = helper._
+import _ from 'lodash'
+import from from 'core-js/library/fn/array/from'
 
-var from = require('core-js/library/fn/array/from')
-var config = require('../../lib/config')
+import helper from '../../lib/helper'
+import config from '../../lib/config'
 
 // create an array of pattern objects from given strings
 var patterns = (...strings) => strings.map((str) => new config.Pattern(str))
@@ -697,8 +697,8 @@ describe('FileList', () => {
       clock = sinon.useFakeTimers()
       // This hack is needed to ensure lodash is using the fake timers
       // from sinon
-      helper._ = _.runInContext()
       List = proxyquire('../../lib/file-list', {
+        lodash: _.runInContext(),
         helper: helper,
         glob: glob,
         'graceful-fs': mockFs,

test/unit/launchers/base.spec.js

@@ -1,4 +1,5 @@
-var _ = require('../../../lib/helper')._
+import _ from 'lodash'
+
 import BaseLauncher from '../../../lib/launchers/base'
 import {EventEmitter} from '../../../lib/events'
 

test/unit/launchers/process.spec.js

@@ -1,5 +1,6 @@
 import path from 'path'
-var _ = require('../../../lib/helper')._
+import _ from 'lodash'
+
 import BaseLauncher from '../../../lib/launchers/base'
 import RetryLauncher from '../../../lib/launchers/retry'
 import CaptureTimeoutLauncher from '../../../lib/launchers/capture_timeout'

test/unit/launchers/retry.spec.js

@@ -1,7 +1,8 @@
+import _ from 'lodash'
+
 import BaseLauncher from '../../../lib/launchers/base'
 import RetryLauncher from '../../../lib/launchers/retry'
 import {EventEmitter} from '../../../lib/events'
-var _ = require('../../../lib/helper')._
 
 describe('launchers/retry.js', () => {
   var emitter

test/unit/reporter.spec.js

@@ -1,8 +1,9 @@
 import {EventEmitter} from 'events'
-import File from '../../lib/file'
 import {loadFile} from 'mocks'
 import path from 'path'
-var _ = require('../../lib/helper')._
+import _ from 'lodash'
+
+import File from '../../lib/file'
 
 describe('reporter', () => {
   var m