refactor(events): refactor karma EventEmitter (#3012)

lib/events.js

@@ -1,75 +1,58 @@
-var events = require('events')
-var util = require('util')
+'use strict'
 
-var helper = require('./helper')
+const EventEmitter = require('events').EventEmitter
+const helper = require('./helper')
 
-var bindAllEvents = function (object, context) {
-  context = context || this
+function bufferEvents (emitter, eventsToBuffer) {
+  const listeners = []
+  const eventsToReply = []
 
-  var bindMethod = function (method) {
-    context.on(helper.camelToSnake(method.substr(2)), function () {
-      var args = Array.prototype.slice.call(arguments, 0)
-      args.push(context)
-      object[method].apply(object, args)
-    })
+  function genericListener () {
+    eventsToReply.push(Array.from(arguments))
   }
 
-  for (var method in object) {
-    if (helper.isFunction(object[method]) && method.substr(0, 2) === 'on') {
-      bindMethod(method)
-    }
-  }
-}
-
-var bufferEvents = function (emitter, eventsToBuffer) {
-  var listeners = []
-  var eventsToReply = []
-  var genericListener = function () {
-    eventsToReply.push(Array.prototype.slice.call(arguments))
-  }
-
-  eventsToBuffer.forEach(function (eventName) {
-    var listener = genericListener.bind(null, eventName)
+  eventsToBuffer.forEach((eventName) => {
+    const listener = genericListener.bind(null, eventName)
     listeners.push(listener)
     emitter.on(eventName, listener)
   })
 
   return function () {
-    if (!eventsToReply) {
-      return
-    }
-
-    // remove all buffering listeners
-    listeners.forEach(function (listener, i) {
+    listeners.forEach((listener, i) => {
       emitter.removeListener(eventsToBuffer[i], listener)
     })
 
-    // reply
-    eventsToReply.forEach(function (args) {
-      events.EventEmitter.prototype.emit.apply(emitter, args)
+    eventsToReply.forEach((args) => {
+      EventEmitter.prototype.emit.apply(emitter, args)
     })
 
-    // free-up
-    listeners = eventsToReply = null
+    listeners.length = 0
+    eventsToReply.length = 0
   }
 }
 
-// TODO(vojta): log.debug all events
-var EventEmitter = function () {
-  this.bind = bindAllEvents
+class KarmaEventEmitter extends EventEmitter {
+  bind (object) {
+    Object.keys(object).forEach((method) => {
+      if (method.startsWith('on') && helper.isFunction(object[method])) {
+        this.on(helper.camelToSnake(method.substr(2)), function () {
+          object[method].apply(object, Array.from(arguments).concat(this))
+        })
+      }
+    })
+  }
 
-  this.emitAsync = function (name) {
+  emitAsync (name) {
     // TODO(vojta): allow passing args
     // TODO(vojta): ignore/throw if listener call done() multiple times
-    var pending = this.listeners(name).length
-    var deferred = helper.defer()
-    var done = function () {
+    let pending = this.listeners(name).length
+    const deferred = helper.defer()
+
+    this.emit(name, () => {
       if (!--pending) {
         deferred.resolve()
       }
-    }
-
-    this.emit(name, done)
+    })
 
     if (!pending) {
       deferred.resolve()
@@ -79,9 +62,5 @@ var EventEmitter = function () {
   }
 }
 
-util.inherits(EventEmitter, events.EventEmitter)
-
-// PUBLISH
-exports.EventEmitter = EventEmitter
-exports.bindAll = bindAllEvents
+exports.EventEmitter = KarmaEventEmitter
 exports.bufferEvents = bufferEvents

lib/launchers/base.js

@@ -24,7 +24,9 @@ var BaseLauncher = function (id, emitter) {
   Object.keys(EventEmitter.prototype).forEach(function (method) {
     this[method] = EventEmitter.prototype[method]
   }, this)
-  KarmaEventEmitter.call(this)
+
+  this.bind = KarmaEventEmitter.prototype.bind.bind(this)
+  this.emitAsync = KarmaEventEmitter.prototype.emitAsync.bind(this)
 
   this.id = id
   this.state = null

lib/server.js

@@ -21,7 +21,8 @@ var FileList = require('./file-list')
 var reporter = require('./reporter')
 var helper = require('./helper')
 var events = require('./events')
-var EventEmitter = events.EventEmitter
+var KarmaEventEmitter = events.EventEmitter
+var EventEmitter = require('events').EventEmitter
 var Executor = require('./executor')
 var Browser = require('./browser')
 var BrowserCollection = require('./browser_collection')
@@ -32,7 +33,7 @@ const karmaJsPath = path.join(__dirname, '/../static/karma.js')
 const contextJsPath = path.join(__dirname, '/../static/context.js')
 
 // Dynamic dependence on brwoserify
-var browserify = null;
+var browserify = null
 
 /**
  * Bundles a static resource using Browserify.
@@ -71,7 +72,12 @@ function createSocketIoServer (webServer, executor, config) {
 
 // Constructor
 var Server = function (cliOptions, done) {
-  EventEmitter.call(this)
+  Object.keys(EventEmitter.prototype).forEach(function (method) {
+    this[method] = EventEmitter.prototype[method]
+  }, this)
+
+  this.bind = KarmaEventEmitter.prototype.bind.bind(this)
+  this.emitAsync = KarmaEventEmitter.prototype.emitAsync.bind(this)
 
   logger.setupFromConfig(cliOptions)
 
@@ -156,7 +162,7 @@ Server.prototype.refreshFiles = function () {
 // ---------------
 
 Server.prototype._start = function (config, launcher, preprocess, fileList,
-                                    capturedBrowsers, executor, done) {
+  capturedBrowsers, executor, done) {
   var self = this
   if (config.detached) {
     this._detach(config, done)

test/unit/events.spec.js

@@ -1,4 +1,4 @@
-var e = require('../../lib/events')
+const e = require('../../lib/events')
 
 describe('events', () => {
   var emitter
@@ -98,7 +98,7 @@ describe('events', () => {
     it('should take emitter as second argument', () => {
       var object = sinon.stub({onFoo: () => {}})
 
-      e.bindAll(object, emitter)
+      emitter.bind(object)
       emitter.emit('foo')
       emitter.emit('bar')
 
@@ -108,7 +108,7 @@ describe('events', () => {
     it('should append "context" to event arguments', () => {
       var object = sinon.stub({onFoo: () => {}})
 
-      e.bindAll(object, emitter)
+      emitter.bind(object)
       emitter.emit('foo', 'event-argument')
 
       expect(object.onFoo).to.have.been.calledWith('event-argument', emitter)