basant307/AI_Governance_Project

1'use strict';2 3var common = require('./common');4var EventEmitter = require('../').EventEmitter;5var once = require('../').once;6var has = require('has');7var assert = require('assert');8 9function Event(type) {10  this.type = type;11}12 13function EventTargetMock() {14  this.events = {};15 16  this.addEventListener = common.mustCall(this.addEventListener);17  this.removeEventListener = common.mustCall(this.removeEventListener);18}19 20EventTargetMock.prototype.addEventListener = function addEventListener(name, listener, options) {21  if (!(name in this.events)) {22    this.events[name] = { listeners: [], options: options || {} }23  }24  this.events[name].listeners.push(listener);25};26 27EventTargetMock.prototype.removeEventListener = function removeEventListener(name, callback) {28  if (!(name in this.events)) {29    return;30  }31  var event = this.events[name];32  var stack = event.listeners;33 34  for (var i = 0, l = stack.length; i < l; i++) {35    if (stack[i] === callback) {36      stack.splice(i, 1);37      if (stack.length === 0) {38        delete this.events[name];39      }40      return;41    }42  }43};44 45EventTargetMock.prototype.dispatchEvent = function dispatchEvent(arg) {46  if (!(arg.type in this.events)) {47    return true;48  }49 50  var event = this.events[arg.type];51  var stack = event.listeners.slice();52 53  for (var i = 0, l = stack.length; i < l; i++) {54    stack[i].call(null, arg);55    if (event.options.once) {56      this.removeEventListener(arg.type, stack[i]);57    }58  }59  return !arg.defaultPrevented;60};61 62function onceAnEvent() {63  var ee = new EventEmitter();64 65  process.nextTick(function () {66    ee.emit('myevent', 42);67  });68 69  return once(ee, 'myevent').then(function (args) {70    var value = args[0]71    assert.strictEqual(value, 42);72    assert.strictEqual(ee.listenerCount('error'), 0);73    assert.strictEqual(ee.listenerCount('myevent'), 0);74  });75}76 77function onceAnEventWithTwoArgs() {78  var ee = new EventEmitter();79 80  process.nextTick(function () {81    ee.emit('myevent', 42, 24);82  });83 84  return once(ee, 'myevent').then(function (value) {85    assert.strictEqual(value.length, 2);86    assert.strictEqual(value[0], 42);87    assert.strictEqual(value[1], 24);88  });89}90 91function catchesErrors() {92  var ee = new EventEmitter();93 94  var expected = new Error('kaboom');95  var err;96  process.nextTick(function () {97    ee.emit('error', expected);98  });99 100  return once(ee, 'myevent').then(function () {101    throw new Error('should reject')102  }, function (err) {103    assert.strictEqual(err, expected);104    assert.strictEqual(ee.listenerCount('error'), 0);105    assert.strictEqual(ee.listenerCount('myevent'), 0);106  });107}108 109function stopListeningAfterCatchingError() {110  var ee = new EventEmitter();111 112  var expected = new Error('kaboom');113  var err;114  process.nextTick(function () {115    ee.emit('error', expected);116    ee.emit('myevent', 42, 24);117  });118 119  // process.on('multipleResolves', common.mustNotCall());120 121  return once(ee, 'myevent').then(common.mustNotCall, function (err) {122    // process.removeAllListeners('multipleResolves');123    assert.strictEqual(err, expected);124    assert.strictEqual(ee.listenerCount('error'), 0);125    assert.strictEqual(ee.listenerCount('myevent'), 0);126  });127}128 129function onceError() {130  var ee = new EventEmitter();131 132  var expected = new Error('kaboom');133  process.nextTick(function () {134    ee.emit('error', expected);135  });136 137  var promise = once(ee, 'error');138  assert.strictEqual(ee.listenerCount('error'), 1);139  return promise.then(function (args) {140    var err = args[0]141    assert.strictEqual(err, expected);142    assert.strictEqual(ee.listenerCount('error'), 0);143    assert.strictEqual(ee.listenerCount('myevent'), 0);144  });145}146 147function onceWithEventTarget() {148  var et = new EventTargetMock();149  var event = new Event('myevent');150  process.nextTick(function () {151    et.dispatchEvent(event);152  });153  return once(et, 'myevent').then(function (args) {154    var value = args[0];155    assert.strictEqual(value, event);156    assert.strictEqual(has(et.events, 'myevent'), false);157  });158}159 160function onceWithEventTargetError() {161  var et = new EventTargetMock();162  var error = new Event('error');163  process.nextTick(function () {164    et.dispatchEvent(error);165  });166  return once(et, 'error').then(function (args) {167    var err = args[0];168    assert.strictEqual(err, error);169    assert.strictEqual(has(et.events, 'error'), false);170  });171}172 173function prioritizesEventEmitter() {174  var ee = new EventEmitter();175  ee.addEventListener = assert.fail;176  ee.removeAllListeners = assert.fail;177  process.nextTick(function () {178    ee.emit('foo');179  });180  return once(ee, 'foo');181}182 183var allTests = [184  onceAnEvent(),185  onceAnEventWithTwoArgs(),186  catchesErrors(),187  stopListeningAfterCatchingError(),188  onceError(),189  onceWithEventTarget(),190  onceWithEventTargetError(),191  prioritizesEventEmitter()192];193 194var hasBrowserEventTarget = false;195try {196  hasBrowserEventTarget = typeof (new window.EventTarget().addEventListener) === 'function' &&197    new window.Event('xyz').type === 'xyz';198} catch (err) {}199 200if (hasBrowserEventTarget) {201  var onceWithBrowserEventTarget = function onceWithBrowserEventTarget() {202    var et = new window.EventTarget();203    var event = new window.Event('myevent');204    process.nextTick(function () {205      et.dispatchEvent(event);206    });207    return once(et, 'myevent').then(function (args) {208      var value = args[0];209      assert.strictEqual(value, event);210      assert.strictEqual(has(et.events, 'myevent'), false);211    });212  }213 214  var onceWithBrowserEventTargetError = function onceWithBrowserEventTargetError() {215    var et = new window.EventTarget();216    var error = new window.Event('error');217    process.nextTick(function () {218      et.dispatchEvent(error);219    });220    return once(et, 'error').then(function (args) {221      var err = args[0];222      assert.strictEqual(err, error);223      assert.strictEqual(has(et.events, 'error'), false);224    });225  }226 227  common.test.comment('Testing with browser built-in EventTarget');228  allTests.push([229    onceWithBrowserEventTarget(),230    onceWithBrowserEventTargetError()231  ]);232}233 234module.exports = Promise.all(allTests);235