| // 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. |
| * @private @const |
| */ |
| 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; |
| }; |