Adding additional unit tests (#406)

* Creating new test class for RemoveEmptyItems

* Adding tests for AddItemToBasket in BasketService

* Removing unused GetBasketItemCountAsync

* Adding tests for BasketWithItemsSpecification

* Adding CustomerORdersWithItemsSpecification tests

* Adding CatalogFilterPaginatedSpecifciation tests

* Adding CatalogItemsSpecification tests

src/ApplicationCore/Interfaces/IBasketService.cs

@@ -5,7 +5,6 @@ namespace Microsoft.eShopWeb.ApplicationCore.Interfaces
 {
     public interface IBasketService
     {
-        Task<int> GetBasketItemCountAsync(string userName);
         Task TransferBasketAsync(string anonymousId, string userName);
         Task AddItemToBasket(int basketId, int catalogItemId, decimal price, int quantity = 1);
         Task SetQuantities(int basketId, Dictionary<string, int> quantities);