public void FailedCallToProductCatalogRepository_ShowsAlert()
 {
     var alertCalled = false;
     var productCatalogRepository = new MockProductCatalogRepository();
     var navService = new MockNavigationService();
     productCatalogRepository.GetRootCategoriesAsyncDelegate = (maxAmmountOfProducts) =>
     {
         throw new Exception();
     };
     var alertMessageService = new MockAlertMessageService();
     alertMessageService.ShowAsyncDelegate = (s, s1) =>
     {
         alertCalled = true;
         Assert.AreEqual("ErrorServiceUnreachable", s1);
         return Task.FromResult(string.Empty);
     };
     var target = new HubPageViewModel(productCatalogRepository, navService,
                                                          alertMessageService, new MockResourceLoader());
     target.OnNavigatedTo(new NavigatedToEventArgs { Parameter = null, NavigationMode = NavigationMode.New }, null);
     
     Assert.IsTrue(alertCalled);
 }
        public void OnNavigatedTo_Fill_RootCategories()
        {
            var repository = new MockProductCatalogRepository();
            var navigationService = new MockNavigationService();

            repository.GetRootCategoriesAsyncDelegate = (maxAmmountOfProducts) =>
            {
                var categories = new Collection<Category>(new List<Category>{
                    new Category(),
                    new Category(),
                    new Category()
                });

                return Task.FromResult((ICollection<Category>)categories);
            };

            var viewModel = new HubPageViewModel(repository, navigationService, null, null);
            viewModel.OnNavigatedTo(new NavigatedToEventArgs { Parameter = null, NavigationMode = NavigationMode.New }, null);

            Assert.IsNotNull(viewModel.RootCategories);
            Assert.AreEqual(((ICollection<CategoryViewModel>)viewModel.RootCategories).Count, 3);
        }