# Yahoo! UI Library

### yuitest 2.5.1

Yahoo! UI Library > yuitest > Assert.js (source view)

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    YAHOO.namespace("util");

    //-----------------------------------------------------------------------------
    // Assert object
    //-----------------------------------------------------------------------------

    /**
     * The Assert object provides functions to test JavaScript values against
     * known and expected results. Whenever a comparison (assertion) fails,
     * an error is thrown.
     *
     * @namespace YAHOO.util
     * @class Assert
     * @static
     */
    YAHOO.util.Assert = {

        //-------------------------------------------------------------------------
        // Helper Methods
        //-------------------------------------------------------------------------

        /**
         * Formats a message so that it can contain the original assertion message
         * in addition to the custom message.
         * @param {String} customMessage The message passed in by the developer.
         * @param {String} defaultMessage The message created by the error by default.
         * @return {String} The final error message, containing either or both.
         * @protected
         * @static
         * @method _formatMessage
         */
        _formatMessage : function (customMessage /*:String*/, defaultMessage /*:String*/) /*:String*/ {
            var message = customMessage;
            if (YAHOO.lang.isString(customMessage) && customMessage.length > 0){
                return YAHOO.lang.substitute(customMessage, { message: defaultMessage });
            } else {
                return defaultMessage;
            }
        },

        //-------------------------------------------------------------------------
        // Generic Assertion Methods
        //-------------------------------------------------------------------------

        /**
         * Forces an assertion error to occur.
         * @param {String} message (Optional) The message to display with the failure.
         * @method fail
         * @static
         */
        fail : function (message /*:String*/) /*:Void*/ {
            throw new YAHOO.util.AssertionError(this._formatMessage(message, "Test force-failed."));
        },

        //-------------------------------------------------------------------------
        // Equality Assertion Methods
        //-------------------------------------------------------------------------

        /**
         * Asserts that a value is equal to another. This uses the double equals sign
         * so type cohersion may occur.
         * @param {Object} expected The expected value.
         * @param {Object} actual The actual value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method areEqual
         * @static
         */
        areEqual : function (expected /*:Object*/, actual /*:Object*/, message /*:String*/) /*:Void*/ {
            if (expected != actual) {
                throw new YAHOO.util.ComparisonFailure(this._formatMessage(message, "Values should be equal."), expected, actual);
            }
        },

        /**
         * Asserts that a value is not equal to another. This uses the double equals sign
         * so type cohersion may occur.
         * @param {Object} unexpected The unexpected value.
         * @param {Object} actual The actual value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method areNotEqual
         * @static
         */
        areNotEqual : function (unexpected /*:Object*/, actual /*:Object*/,
                             message /*:String*/) /*:Void*/ {
            if (unexpected == actual) {
                throw new YAHOO.util.UnexpectedValue(this._formatMessage(message, "Values should not be equal."), unexpected);
            }
        },

        /**
         * Asserts that a value is not the same as another. This uses the triple equals sign
         * so no type cohersion may occur.
         * @param {Object} unexpected The unexpected value.
         * @param {Object} actual The actual value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method areNotSame
         * @static
         */
        areNotSame : function (unexpected /*:Object*/, actual /*:Object*/, message /*:String*/) /*:Void*/ {
            if (unexpected === actual) {
                throw new YAHOO.util.UnexpectedValue(this._formatMessage(message, "Values should not be the same."), unexpected);
            }
        },

        /**
         * Asserts that a value is the same as another. This uses the triple equals sign
         * so no type cohersion may occur.
         * @param {Object} expected The expected value.
         * @param {Object} actual The actual value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method areSame
         * @static
         */
        areSame : function (expected /*:Object*/, actual /*:Object*/, message /*:String*/) /*:Void*/ {
            if (expected !== actual) {
                throw new YAHOO.util.ComparisonFailure(this._formatMessage(message, "Values should be the same."), expected, actual);
            }
        },

        //-------------------------------------------------------------------------
        // Boolean Assertion Methods
        //-------------------------------------------------------------------------

        /**
         * Asserts that a value is false. This uses the triple equals sign
         * so no type cohersion may occur.
         * @param {Object} actual The actual value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method isFalse
         * @static
         */
        isFalse : function (actual /*:Boolean*/, message /*:String*/) {
            if (false !== actual) {
                throw new YAHOO.util.ComparisonFailure(this._formatMessage(message, "Value should be false."), false, actual);
            }
        },

        /**
         * Asserts that a value is true. This uses the triple equals sign
         * so no type cohersion may occur.
         * @param {Object} actual The actual value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method isTrue
         * @static
         */
        isTrue : function (actual /*:Boolean*/, message /*:String*/) /*:Void*/ {
            if (true !== actual) {
                throw new YAHOO.util.ComparisonFailure(this._formatMessage(message, "Value should be true."), true, actual);
            }

        },

        //-------------------------------------------------------------------------
        // Special Value Assertion Methods
        //-------------------------------------------------------------------------

        /**
         * Asserts that a value is not a number.
         * @param {Object} actual The value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method isNaN
         * @static
         */
        isNaN : function (actual /*:Object*/, message /*:String*/) /*:Void*/{
            if (!isNaN(actual)){
                throw new YAHOO.util.ComparisonFailure(this._formatMessage(message, "Value should be NaN."), NaN, actual);
            }
        },

        /**
         * Asserts that a value is not the special NaN value.
         * @param {Object} actual The value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method isNotNaN
         * @static
         */
        isNotNaN : function (actual /*:Object*/, message /*:String*/) /*:Void*/{
            if (isNaN(actual)){
                throw new YAHOO.util.UnexpectedValue(this._formatMessage(message, "Values should not be NaN."), NaN);
            }
        },

        /**
         * Asserts that a value is not null. This uses the triple equals sign
         * so no type cohersion may occur.
         * @param {Object} actual The actual value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method isNotNull
         * @static
         */
        isNotNull : function (actual /*:Object*/, message /*:String*/) /*:Void*/ {
            if (YAHOO.lang.isNull(actual)) {
                throw new YAHOO.util.UnexpectedValue(this._formatMessage(message, "Values should not be null."), null);
            }
        },

        /**
         * Asserts that a value is not undefined. This uses the triple equals sign
         * so no type cohersion may occur.
         * @param {Object} actual The actual value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method isNotUndefined
         * @static
         */
        isNotUndefined : function (actual /*:Object*/, message /*:String*/) /*:Void*/ {
            if (YAHOO.lang.isUndefined(actual)) {
                throw new YAHOO.util.UnexpectedValue(this._formatMessage(message, "Value should not be undefined."), undefined);
            }
        },

        /**
         * Asserts that a value is null. This uses the triple equals sign
         * so no type cohersion may occur.
         * @param {Object} actual The actual value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method isNull
         * @static
         */
        isNull : function (actual /*:Object*/, message /*:String*/) /*:Void*/ {
            if (!YAHOO.lang.isNull(actual)) {
                throw new YAHOO.util.ComparisonFailure(this._formatMessage(message, "Value should be null."), null, actual);
            }
        },

        /**
         * Asserts that a value is undefined. This uses the triple equals sign
         * so no type cohersion may occur.
         * @param {Object} actual The actual value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method isUndefined
         * @static
         */
        isUndefined : function (actual /*:Object*/, message /*:String*/) /*:Void*/ {
            if (!YAHOO.lang.isUndefined(actual)) {
                throw new YAHOO.util.ComparisonFailure(this._formatMessage(message, "Value should be undefined."), undefined, actual);
            }
        },

        //--------------------------------------------------------------------------
        // Instance Assertion Methods
        //--------------------------------------------------------------------------

        /**
         * Asserts that a value is an array.
         * @param {Object} actual The value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method isArray
         * @static
         */
        isArray : function (actual /*:Object*/, message /*:String*/) /*:Void*/ {
            if (!YAHOO.lang.isArray(actual)){
                throw new YAHOO.util.UnexpectedValue(this._formatMessage(message, "Value should be an array."), actual);
            }
        },

        /**
         * Asserts that a value is a Boolean.
         * @param {Object} actual The value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method isBoolean
         * @static
         */
        isBoolean : function (actual /*:Object*/, message /*:String*/) /*:Void*/ {
            if (!YAHOO.lang.isBoolean(actual)){
                throw new YAHOO.util.UnexpectedValue(this._formatMessage(message, "Value should be a Boolean."), actual);
            }
        },

        /**
         * Asserts that a value is a function.
         * @param {Object} actual The value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method isFunction
         * @static
         */
        isFunction : function (actual /*:Object*/, message /*:String*/) /*:Void*/ {
            if (!YAHOO.lang.isFunction(actual)){
                throw new YAHOO.util.UnexpectedValue(this._formatMessage(message, "Value should be a function."), actual);
            }
        },

        /**
         * Asserts that a value is an instance of a particular object. This may return
         * incorrect results when comparing objects from one frame to constructors in
         * another frame. For best results, don't use in a cross-frame manner.
         * @param {Function} expected The function that the object should be an instance of.
         * @param {Object} actual The object to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method isInstanceOf
         * @static
         */
        isInstanceOf : function (expected /*:Function*/, actual /*:Object*/, message /*:String*/) /*:Void*/ {
            if (!(actual instanceof expected)){
                throw new YAHOO.util.ComparisonFailure(this._formatMessage(message, "Value isn't an instance of expected type."), expected, actual);
            }
        },

        /**
         * Asserts that a value is a number.
         * @param {Object} actual The value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method isNumber
         * @static
         */
        isNumber : function (actual /*:Object*/, message /*:String*/) /*:Void*/ {
            if (!YAHOO.lang.isNumber(actual)){
                throw new YAHOO.util.UnexpectedValue(this._formatMessage(message, "Value should be a number."), actual);
            }
        },

        /**
         * Asserts that a value is an object.
         * @param {Object} actual The value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method isObject
         * @static
         */
        isObject : function (actual /*:Object*/, message /*:String*/) /*:Void*/ {
            if (!YAHOO.lang.isObject(actual)){
                throw new YAHOO.util.UnexpectedValue(this._formatMessage(message, "Value should be an object."), actual);
            }
        },

        /**
         * Asserts that a value is a string.
         * @param {Object} actual The value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method isString
         * @static
         */
        isString : function (actual /*:Object*/, message /*:String*/) /*:Void*/ {
            if (!YAHOO.lang.isString(actual)){
                throw new YAHOO.util.UnexpectedValue(this._formatMessage(message, "Value should be a string."), actual);
            }
        },

        /**
         * Asserts that a value is of a particular type.
         * @param {String} expectedType The expected type of the variable.
         * @param {Object} actualValue The actual value to test.
         * @param {String} message (Optional) The message to display if the assertion fails.
         * @method isTypeOf
         * @static
         */
        isTypeOf : function (expectedType /*:String*/, actualValue /*:Object*/, message /*:String*/) /*:Void*/{
            if (typeof actualValue != expectedType){
                throw new YAHOO.util.ComparisonFailure(this._formatMessage(message, "Value should be of type " + expected + "."), expected, typeof actual);
            }
        }
    };

    //-----------------------------------------------------------------------------
    // Assertion errors
    //-----------------------------------------------------------------------------

    /**
     * AssertionError is thrown whenever an assertion fails. It provides methods
     * to more easily get at error information and also provides a base class
     * from which more specific assertion errors can be derived.
     *
     * @param {String} message The message to display when the error occurs.
     * @namespace YAHOO.util
     * @class AssertionError
     * @extends Error
     * @constructor
     */
    YAHOO.util.AssertionError = function (message /*:String*/){

        //call superclass
        arguments.callee.superclass.constructor.call(this, message);

        /*
         * Error message. Must be duplicated to ensure browser receives it.
         * @type String
         * @property message
         */
        this.message /*:String*/ = message;

        /**
         * The name of the error that occurred.
         * @type String
         * @property name
         */
        this.name /*:String*/ = "AssertionError";
    };

    //inherit methods
    YAHOO.lang.extend(YAHOO.util.AssertionError, Error, {

        /**
         * Returns a fully formatted error for an assertion failure. This should
         * be overridden by all subclasses to provide specific information.
         * @method getMessage
         * @return {String} A string describing the error.
         */
        getMessage : function () /*:String*/ {
            return this.message;
        },

        /**
         * Returns a string representation of the error.
         * @method toString
         * @return {String} A string representation of the error.
         */
        toString : function () /*:String*/ {
            return this.name + ": " + this.getMessage();
        },

        /**
         * Returns a primitive value version of the error. Same as toString().
         * @method valueOf
         * @return {String} A primitive value version of the error.
         */
        valueOf : function () /*:String*/ {
            return this.toString();
        }

    });

    /**
     * ComparisonFailure is subclass of AssertionError 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 YAHOO.util
     * @extends YAHOO.util.AssertionError
     * @class ComparisonFailure
     * @constructor
     */
    YAHOO.util.ComparisonFailure = function (message /*:String*/, expected /*:Object*/, actual /*:Object*/){

        //call superclass
        arguments.callee.superclass.constructor.call(this, message);

        /**
         * The expected value.
         * @type Object
         * @property expected
         */
        this.expected /*:Object*/ = expected;

        /**
         * The actual value.
         * @type Object
         * @property actual
         */
        this.actual /*:Object*/ = actual;

        /**
         * The name of the error that occurred.
         * @type String
         * @property name
         */
        this.name /*:String*/ = "ComparisonFailure";

    };

    //inherit methods
    YAHOO.lang.extend(YAHOO.util.ComparisonFailure, YAHOO.util.AssertionError, {

        /**
         * Returns a fully formatted error for an assertion failure. This message
         * provides information about the expected and actual values.
         * @method toString
         * @return {String} A string describing the error.
         */
        getMessage : function () /*:String*/ {
            return this.message + "\nExpected: " + this.expected + " (" + (typeof this.expected) + ")"  +
                "\nActual:" + this.actual + " (" + (typeof this.actual) + ")";
        }

    });

    /**
     * UnexpectedValue is subclass of AssertionError that is thrown whenever
     * a value was unexpected in its scope. This typically means that a test
     * was performed to determine that a value was *not* equal to a certain
     * value.
     *
     * @param {String} message The message to display when the error occurs.
     * @param {Object} unexpected The unexpected value.
     * @namespace YAHOO.util
     * @extends YAHOO.util.AssertionError
     * @class UnexpectedValue
     * @constructor
     */
    YAHOO.util.UnexpectedValue = function (message /*:String*/, unexpected /*:Object*/){

        //call superclass
        arguments.callee.superclass.constructor.call(this, message);

        /**
         * The unexpected value.
         * @type Object
         * @property unexpected
         */
        this.unexpected /*:Object*/ = unexpected;

        /**
         * The name of the error that occurred.
         * @type String
         * @property name
         */
        this.name /*:String*/ = "UnexpectedValue";

    };

    //inherit methods
    YAHOO.lang.extend(YAHOO.util.UnexpectedValue, YAHOO.util.AssertionError, {

        /**
         * Returns a fully formatted error for an assertion failure. The message
         * contains information about the unexpected value that was encountered.
         * @method getMessage
         * @return {String} A string describing the error.
         */
        getMessage : function () /*:String*/ {
            return this.message + "\nUnexpected: " + this.unexpected + " (" + (typeof this.unexpected) + ") ";
        }

    });

    /**
     * ShouldFail is subclass of AssertionError that is thrown whenever
     * a test was expected to fail but did not.
     *
     * @param {String} message The message to display when the error occurs.
     * @namespace YAHOO.util
     * @extends YAHOO.util.AssertionError
     * @class ShouldFail
     * @constructor
     */
    YAHOO.util.ShouldFail = function (message /*:String*/){

        //call superclass
        arguments.callee.superclass.constructor.call(this, message || "This test should fail but didn't.");

        /**
         * The name of the error that occurred.
         * @type String
         * @property name
         */
        this.name /*:String*/ = "ShouldFail";

    };

    //inherit methods
    YAHOO.lang.extend(YAHOO.util.ShouldFail, YAHOO.util.AssertionError);

    /**
     * ShouldError is subclass of AssertionError that is thrown whenever
     * a test is expected to throw an error but doesn't.
     *
     * @param {String} message The message to display when the error occurs.
     * @namespace YAHOO.util
     * @extends YAHOO.util.AssertionError
     * @class ShouldError
     * @constructor
     */
    YAHOO.util.ShouldError = function (message /*:String*/){

        //call superclass
        arguments.callee.superclass.constructor.call(this, message || "This test should have thrown an error but didn't.");

        /**
         * The name of the error that occurred.
         * @type String
         * @property name
         */
        this.name /*:String*/ = "ShouldError";

    };

    //inherit methods
    YAHOO.lang.extend(YAHOO.util.ShouldError, YAHOO.util.AssertionError);

    /**
     * UnexpectedError is subclass of AssertionError that is thrown whenever
     * an error occurs within the course of a test and the test was not expected
     * to throw an error.
     *
     * @param {Error} cause The unexpected error that caused this error to be
     *                      thrown.
     * @namespace YAHOO.util
     * @extends YAHOO.util.AssertionError
     * @class UnexpectedError
     * @constructor
     */
    YAHOO.util.UnexpectedError = function (cause /*:Object*/){

        //call superclass
        arguments.callee.superclass.constructor.call(this, "Unexpected error: " + cause.message);

        /**
         * The unexpected error that occurred.
         * @type Error
         * @property cause
         */
        this.cause /*:Error*/ = cause;

        /**
         * The name of the error that occurred.
         * @type String
         * @property name
         */
        this.name /*:String*/ = "UnexpectedError";

        /**
         * Stack information for the error (if provided).
         * @type String
         * @property stack
         */
        this.stack /*:String*/ = cause.stack;

    };

    //inherit methods
    YAHOO.lang.extend(YAHOO.util.UnexpectedError, YAHOO.util.AssertionError);

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