Refactoring and Adding Tests (#28)

* Introducing repository and refactoring services.
Changing entities to use int keys everywhere.

* Refactoring application services to live in web project and only reference repositories, not EF contexts.

* Cleaning up implementations

* Moving logic out of CatalogController
Moving entity knowledge out of viewmodels.

* Implementing specification includes better for catalogservice

* Cleaning up and adding specification unit tests

src/ApplicationCore/Interfaces/IAppLogger.cs

@@ -1,5 +1,9 @@
 namespace ApplicationCore.Interfaces
 {
+    /// <summary>
+    /// This type eliminates the need to depend directly on the ASP.NET Core logging types.
+    /// </summary>
+    /// <typeparam name="T"></typeparam>
     public interface IAppLogger<T>
     {
         void LogWarning(string message, params object[] args);

src/ApplicationCore/Interfaces/IBasketService.cs

@@ -1,15 +0,0 @@
-using Microsoft.eShopWeb.ApplicationCore.Entities;
-using System.Threading.Tasks;
-
-namespace ApplicationCore.Interfaces
-{
-    public interface IBasketService
-    {
-        Task<Basket> GetBasket(string basketId);
-        Task<Basket> CreateBasket();
-        Task<Basket> CreateBasketForUser(string userId);
-
-        Task AddItemToBasket(Basket basket, int productId, int quantity);
-        //Task UpdateBasket(Basket basket);
-    }
-}

src/ApplicationCore/Interfaces/IRepository.cs

@@ -0,0 +1,18 @@
+using Microsoft.eShopWeb.ApplicationCore.Entities;
+using System;
+using System.Collections.Generic;
+using System.Linq.Expressions;
+
+namespace ApplicationCore.Interfaces
+{
+
+    public interface IRepository<T> where T : BaseEntity
+    {
+        T GetById(int id);
+        List<T> List();
+        List<T> List(ISpecification<T> spec);
+        T Add(T entity);
+        void Update(T entity);
+        void Delete(T entity);
+    }
+}

src/ApplicationCore/Interfaces/ISpecification.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Linq.Expressions;
+
+namespace ApplicationCore.Interfaces
+{
+    public interface ISpecification<T>
+    {
+        Expression<Func<T, bool>> Criteria { get; }
+        List<Expression<Func<T, object>>> Includes { get; }
+        void AddInclude(Expression<Func<T, object>> includeExpression);
+    }
+}

src/ApplicationCore/Interfaces/IUriComposer.cs

@@ -1,4 +1,7 @@
-namespace ApplicationCore.Interfaces
+using Microsoft.eShopWeb.ApplicationCore.Entities;
+using System.Collections.Generic;
+
+namespace ApplicationCore.Interfaces
 {
 
     public interface IUriComposer