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node_modules/selenium-webdriver/lib/goog/testing/propertyreplacer.js
Maintainability
65.09
Lines of code
227
Difficulty
64.09
Estimated Errors
1.19
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// Copyright 2008 The Closure Library Authors. All Rights Reserved. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS-IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. /** * @fileoverview Helper class for creating stubs for testing. * */ goog.provide('goog.testing.PropertyReplacer'); /** @suppress {extraRequire} Needed for some tests to compile. */ goog.require('goog.testing.ObjectPropertyString'); goog.require('goog.userAgent'); /** * Helper class for stubbing out variables and object properties for unit tests. * This class can change the value of some variables before running the test * cases, and to reset them in the tearDown phase. * See googletest.StubOutForTesting as an analogy in Python: * http://protobuf.googlecode.com/svn/trunk/python/stubout.py * * Example usage: * <pre>var stubs = new goog.testing.PropertyReplacer(); * * function setUp() { * // Mock functions used in all test cases. * stubs.set(Math, 'random', function() { * return 4; // Chosen by fair dice roll. Guaranteed to be random. * }); * } * * function tearDown() { * stubs.reset(); * } * * function testThreeDice() { * // Mock a constant used only in this test case. * stubs.set(goog.global, 'DICE_COUNT', 3); * assertEquals(12, rollAllDice()); * }</pre> * * Constraints on altered objects: * <ul> * <li>DOM subclasses aren't supported. * <li>The value of the objects' constructor property must either be equal to * the real constructor or kept untouched. * </ul> * * @constructor * @final */ goog.testing.PropertyReplacer = function() { /** * Stores the values changed by the set() method in chronological order. * Its items are objects with 3 fields: 'object', 'key', 'value'. The * original value for the given key in the given object is stored under the * 'value' key. * @type {Array.<Object>} * @private */ this.original_ = []; }; /** * Indicates that a key didn't exist before having been set by the set() method. * @type {Object} * @private */ goog.testing.PropertyReplacer.NO_SUCH_KEY_ = {}; /** * Tells if the given key exists in the object. Ignores inherited fields. * @param {Object|Function} obj The JavaScript or native object or function * whose key is to be checked. * @param {string} key The key to check. * @return {boolean} Whether the object has the key as own key. * @private */ goog.testing.PropertyReplacer.hasKey_ = function(obj, key) { if (!(key in obj)) { return false; } // hasOwnProperty is only reliable with JavaScript objects. It returns false // for built-in DOM attributes. if (Object.prototype.hasOwnProperty.call(obj, key)) { return true; } // In all browsers except Opera obj.constructor never equals to Object if // obj is an instance of a native class. In Opera we have to fall back on // examining obj.toString(). if (obj.constructor == Object && (!goog.userAgent.OPERA || Object.prototype.toString.call(obj) == '[object Object]')) { return false; } try { // Firefox hack to consider "className" part of the HTML elements or // "body" part of document. Although they are defined in the prototype of // HTMLElement or Document, accessing them this way throws an exception. // <pre> // var dummy = document.body.constructor.prototype.className // [Exception... "Cannot modify properties of a WrappedNative"] // </pre> var dummy = obj.constructor.prototype[key]; } catch (e) { return true; } return !(key in obj.constructor.prototype); }; /** * Deletes a key from an object. Sets it to undefined or empty string if the * delete failed. * @param {Object|Function} obj The object or function to delete a key from. * @param {string} key The key to delete. * @private */ goog.testing.PropertyReplacer.deleteKey_ = function(obj, key) { try { delete obj[key]; // Delete has no effect for built-in properties of DOM nodes in FF. if (!goog.testing.PropertyReplacer.hasKey_(obj, key)) { return; } } catch (e) { // IE throws TypeError when trying to delete properties of native objects // (e.g. DOM nodes or window), even if they have been added by JavaScript. } obj[key] = undefined; if (obj[key] == 'undefined') { // Some properties such as className in IE are always evaluated as string // so undefined will become 'undefined'. obj[key] = ''; } }; /** * Adds or changes a value in an object while saving its original state. * @param {Object|Function} obj The JavaScript or native object or function to * alter. See the constraints in the class description. * @param {string} key The key to change the value for. * @param {*} value The new value to set. */ goog.testing.PropertyReplacer.prototype.set = function(obj, key, value) { var origValue = goog.testing.PropertyReplacer.hasKey_(obj, key) ? obj[key] : goog.testing.PropertyReplacer.NO_SUCH_KEY_; this.original_.push({object: obj, key: key, value: origValue}); obj[key] = value; }; /** * Changes an existing value in an object to another one of the same type while * saving its original state. The advantage of {@code replace} over {@link #set} * is that {@code replace} protects against typos and erroneously passing tests * after some members have been renamed during a refactoring. * @param {Object|Function} obj The JavaScript or native object or function to * alter. See the constraints in the class description. * @param {string} key The key to change the value for. It has to be present * either in {@code obj} or in its prototype chain. * @param {*} value The new value to set. It has to have the same type as the * original value. The types are compared with {@link goog.typeOf}. * @throws {Error} In case of missing key or type mismatch. */ goog.testing.PropertyReplacer.prototype.replace = function(obj, key, value) { if (!(key in obj)) { throw Error('Cannot replace missing property "' + key + '" in ' + obj); } if (goog.typeOf(obj[key]) != goog.typeOf(value)) { throw Error('Cannot replace property "' + key + '" in ' + obj + ' with a value of different type'); } this.set(obj, key, value); }; /** * Builds an object structure for the provided namespace path. Doesn't * overwrite those prefixes of the path that are already objects or functions. * @param {string} path The path to create or alter, e.g. 'goog.ui.Menu'. * @param {*} value The value to set. */ goog.testing.PropertyReplacer.prototype.setPath = function(path, value) { var parts = path.split('.'); var obj = goog.global; for (var i = 0; i < parts.length - 1; i++) { var part = parts[i]; if (part == 'prototype' && !obj[part]) { throw Error('Cannot set the prototype of ' + parts.slice(0, i).join('.')); } if (!goog.isObject(obj[part]) && !goog.isFunction(obj[part])) { this.set(obj, part, {}); } obj = obj[part]; } this.set(obj, parts[parts.length - 1], value); }; /** * Deletes the key from the object while saving its original value. * @param {Object|Function} obj The JavaScript or native object or function to * alter. See the constraints in the class description. * @param {string} key The key to delete. */ goog.testing.PropertyReplacer.prototype.remove = function(obj, key) { if (goog.testing.PropertyReplacer.hasKey_(obj, key)) { this.original_.push({object: obj, key: key, value: obj[key]}); goog.testing.PropertyReplacer.deleteKey_(obj, key); } }; /** * Resets all changes made by goog.testing.PropertyReplacer.prototype.set. */ goog.testing.PropertyReplacer.prototype.reset = function() { for (var i = this.original_.length - 1; i >= 0; i--) { var original = this.original_[i]; if (original.value == goog.testing.PropertyReplacer.NO_SUCH_KEY_) { goog.testing.PropertyReplacer.deleteKey_(original.object, original.key); } else { original.object[original.key] = original.value; } delete this.original_[i]; } this.original_.length = 0; };