# Yahoo! UI Library

### test 3.0.0

Yahoo! UI Library > test > Mock.js (source view)
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        /**
         * Creates a new mock object.
         * @class Mock
         * @constructor
         * @param {Object} template (Optional) An object whose methods
         *      should be stubbed out on the mock object.
         */
        Y.Mock = function(template){

            //use blank object is nothing is passed in
            template = template || {};

            var mock = null;

            //try to create mock that keeps prototype chain intact
            try {
                mock = Y.Object(template);
            } catch (ex) {
                mock = {};
                Y.log("Couldn't create mock with prototype.", "warn", "Mock");
            }

            //create new versions of the methods so that they don't actually do anything
            Y.Object.each(template, function(name){
                if (Y.Lang.isFunction(template[name])){
                    mock[name] = function(){
                        Y.Assert.fail("Method " + name + "() was called but was not expected to be.");
                    };
                }
            });

            //return it
            return mock;
        };

        /**
         * Assigns an expectation to a mock object. This is used to create
         * methods and properties on the mock object that are monitored for
         * calls and changes, respectively.
         * @param {Object} mock The object to add the expectation to.
         * @param {Object} expectation An object defining the expectation. For
         *      a method, the keys "method" and "args" are required with
         *      an optional "returns" key available. For properties, the keys
         *      "property" and "value" are required.
         * @return {void}
         * @method expect
         * @static
         */
        Y.Mock.expect = function(mock /*:Object*/, expectation /*:Object*/){

            //make sure there's a place to store the expectations
            if (!mock.__expectations) {
                mock.__expectations = {};
            }

            //method expectation
            if (expectation.method){
                var name = expectation.method,
                    args = expectation.args || expectation.arguments || [],
                    result = expectation.returns,
                    callCount = Y.Lang.isNumber(expectation.callCount) ? expectation.callCount : 1,
                    error = expectation.error,
                    run = expectation.run || function(){};

                //save expectations
                mock.__expectations[name] = expectation;
                expectation.callCount = callCount;
                expectation.actualCallCount = 0;

                //process arguments
                Y.Array.each(args, function(arg, i, array){
                    if (!(array[i] instanceof Y.Mock.Value)){
                        array[i] = Y.Mock.Value(Y.Assert.areSame, [arg], "Argument " + i + " of " + name + "() is incorrect.");
                    }
                });

                //if the method is expected to be called
                if (callCount > 0){
                    mock[name] = function(){
                        try {
                            expectation.actualCallCount++;
                            Y.Assert.areEqual(args.length, arguments.length, "Method " + name + "() passed incorrect number of arguments.");
                            for (var i=0, len=args.length; i < len; i++){
                                //if (args[i]){
                                    args[i].verify(arguments[i]);
                                //} else {
                                //    Y.Assert.fail("Argument " + i + " (" + arguments[i] + ") was not expected to be used.");
                                //}

                            }

                            run.apply(this, arguments);

                            if (error){
                                throw error;
                            }
                        } catch (ex){
                            //route through TestRunner for proper handling
                            Y.Test.Runner._handleError(ex);
                        }

                        return result;
                    };
                } else {

                    //method should fail if called when not expected
                    mock[name] = function(){
                        try {
                            Y.Assert.fail("Method " + name + "() should not have been called.");
                        } catch (ex){
                            //route through TestRunner for proper handling
                            Y.Test.Runner._handleError(ex);
                        }
                    };
                }
            } else if (expectation.property){
                //save expectations
                mock.__expectations[name] = expectation;
            }
        };

        /**
         * Verifies that all expectations of a mock object have been met and
         * throws an assertion error if not.
         * @param {Object} mock The object to verify..
         * @return {void}
         * @method verify
         * @static
         */
        Y.Mock.verify = function(mock /*:Object*/){
            try {
                Y.Object.each(mock.__expectations, function(expectation){
                    if (expectation.method) {
                        Y.Assert.areEqual(expectation.callCount, expectation.actualCallCount, "Method " + expectation.method + "() wasn't called the expected number of times.");
                    } else if (expectation.property){
                        Y.Assert.areEqual(expectation.value, mock[expectation.property], "Property " + expectation.property + " wasn't set to the correct value.");
                    }
                });
            } catch (ex){
                //route through TestRunner for proper handling
                Y.Test.Runner._handleError(ex);
            }
        };

        Y.Mock.Value = function(method, originalArgs, message){
            if (this instanceof Y.Mock.Value){
                this.verify = function(value){
                    var args = [].concat(originalArgs || []);
                    args.push(value);
                    args.push(message);
                    method.apply(null, args);
                };
            } else {
                return new Y.Mock.Value(method, originalArgs, message);
            }
        };

        Y.Mock.Value.Any        = Y.Mock.Value(function(){});
        Y.Mock.Value.Boolean    = Y.Mock.Value(Y.Assert.isBoolean);
        Y.Mock.Value.Number     = Y.Mock.Value(Y.Assert.isNumber);
        Y.Mock.Value.String     = Y.Mock.Value(Y.Assert.isString);
        Y.Mock.Value.Object     = Y.Mock.Value(Y.Assert.isObject);
        Y.Mock.Value.Function   = Y.Mock.Value(Y.Assert.isFunction);

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