/**
                             * ComparisonFailure is subclass of Error that is thrown whenever
                             * a comparison between two values fails. It provides mechanisms to retrieve
                             * both the expected and actual value.
                             *
                             * @param {String} message The message to display when the error occurs.
                             * @param {Object} expected The expected value.
                             * @param {Object} actual The actual value that caused the assertion to fail.
                             * @namespace Test
                             * @extends AssertionError
                             * @module test
                             * @class ComparisonFailure
                             * @constructor
                             */
                            YUITest.ComparisonFailure = function (message, expected, actual){
                            
                                //call superclass
                                YUITest.AssertionError.call(this, message);
                            
                                /**
                                 * The expected value.
                                 * @type Object
                                 * @property expected
                                 */
                                this.expected = expected;
                            
                                /**
                                 * The actual value.
                                 * @type Object
                                 * @property actual
                                 */
                                this.actual = actual;
                            
                                /**
                                 * The name of the error that occurred.
                                 * @type String
                                 * @property name
                                 */
                                this.name = "ComparisonFailure";
                            
                            };
                            
                            //inherit from YUITest.AssertionError
                            YUITest.ComparisonFailure.prototype = new YUITest.AssertionError;
                            
                            //restore constructor
                            YUITest.ComparisonFailure.prototype.constructor = YUITest.ComparisonFailure;
                            
                            /**
                             * Returns a fully formatted error for an assertion failure. This message
                             * provides information about the expected and actual values.
                             * @method getMessage
                             * @return {String} A string describing the error.
                             */
                            YUITest.ComparisonFailure.prototype.getMessage = function(){
                                return this.message + "\nExpected: " + this.expected + " (" + (typeof this.expected) + ")"  +
                                        "\nActual: " + this.actual + " (" + (typeof this.actual) + ")";
                            };