Refactor and update to C# 7 constructs

Controllers/BasketController:
Use Expression Bodied Members.
Delete() should not be 'fire and forget'

Controllers/HomeController:
Expression bodied constructor

IntegrationEvents/EventHandling/ProductPriceChangedIntegratedEventHandler:
Use valueTask to minimize allocations for 'fast path' tasks. One might
believe that
most users would not have the changing item in the basket at any given
time.
Using ValueTask instead of Task, this minimizes allocations to only when
async
work must actually take place.

IntegrationEvents/EventHandling/ProductPriceChangedIntegratedEvent:
Make the properties ReadOnly

Model/Basket:
Use property initializer

Model/RedisBasketRepository:
Remove redundant ToString()
Use elvis operator instead of statement null check

Startup:
remove redundant ToString()

src/Services/Basket/Basket.API/Controllers/BasketController.cs

@@ -18,10 +18,9 @@ namespace Microsoft.eShopOnContainers.Services.Basket.API.Controllers
     {
         private IBasketRepository _repository;
 
-        public BasketController(IBasketRepository repository)
-        {
+        public BasketController(IBasketRepository repository) =>
             _repository = repository;
-        }
+
         // GET api/values/5
         [HttpGet("{id}")]
         public async Task<IActionResult> Get(string id)
@@ -42,9 +41,9 @@ namespace Microsoft.eShopOnContainers.Services.Basket.API.Controllers
 
         // DELETE api/values/5
         [HttpDelete("{id}")]
-        public void Delete(string id)
+        public Task Delete(string id) 
         {
-            _repository.DeleteBasket(id);
+            return _repository.DeleteBasket(id);
         }
     }
 }

src/Services/Basket/Basket.API/Controllers/HomeController.cs

@@ -11,9 +11,7 @@ namespace Microsoft.eShopOnContainers.Services.Basket.API.Controllers
     public class HomeController : Controller
     {
         // GET: /<controller>/
-        public IActionResult Index()
-        {
-            return new RedirectResult("~/swagger/ui");
-        }
+        public IActionResult Index() =>
+            new RedirectResult("~/swagger/ui");
     }
 }

src/Services/Basket/Basket.API/IntegrationEvents/EventHandling/ProductPriceChangedIntegrationEventHandler.cs

@@ -4,6 +4,7 @@ using Microsoft.eShopOnContainers.Services.Basket.API.Model;
 using System.Linq;
 using System.Threading.Tasks;
 
+
 namespace Microsoft.eShopOnContainers.Services.Basket.API.IntegrationEvents.EventHandling
 {
     public class ProductPriceChangedIntegrationEventHandler : IIntegrationEventHandler<ProductPriceChangedIntegrationEvent>
@@ -20,26 +21,29 @@ namespace Microsoft.eShopOnContainers.Services.Basket.API.IntegrationEvents.Even
             foreach (var id in userIds)
             {
                 var basket = await _repository.GetBasket(id);
-                await UpdateBasket(@event.ProductId, @event.NewPrice, basket);                      
+                await UpdateBasket(@event.ProductId, @event.NewPrice, basket);
             }
         }
 
-        private async Task UpdateBasket(int productId, decimal newPrice, CustomerBasket basket)
+        private ValueTask<CustomerBasket> UpdateBasket(int productId, decimal newPrice, CustomerBasket basket)
         {
             var itemsToUpdate = basket?.Items?.Where(x => int.Parse(x.ProductId) == productId).ToList();
             if (itemsToUpdate != null)
             {
                 foreach (var item in itemsToUpdate)
                 {
-                    if(item.UnitPrice != newPrice)
-                    { 
+                    if (item.UnitPrice != newPrice)
+                    {
                         var originalPrice = item.UnitPrice;
                         item.UnitPrice = newPrice;
                         item.OldUnitPrice = originalPrice;
                     }
                 }
-                await _repository.UpdateBasket(basket);
-            }           
+                return new ValueTask<CustomerBasket>(_repository.UpdateBasket(basket));
+            } else
+            {
+                return new ValueTask<CustomerBasket>(default(CustomerBasket));
+            }
         }
     }
 }

src/Services/Basket/Basket.API/IntegrationEvents/Events/ProductPriceChangedIntegrationEvent.cs

@@ -10,11 +10,11 @@ namespace Microsoft.eShopOnContainers.Services.Basket.API.IntegrationEvents.Even
     // An Integration Event is an event that can cause side effects to other microsrvices, Bounded-Contexts or external systems.
     public class ProductPriceChangedIntegrationEvent : IntegrationEvent
     {        
-        public int ProductId { get; private set; }
+        public int ProductId { get; }
 
-        public decimal NewPrice { get; private set; }
+        public decimal NewPrice { get; }
 
-        public decimal OldPrice { get; private set; }
+        public decimal OldPrice { get; }
 
         public ProductPriceChangedIntegrationEvent(int productId, decimal newPrice, decimal oldPrice)
         {

src/Services/Basket/Basket.API/Model/Basket.cs

@@ -8,12 +8,9 @@ namespace Microsoft.eShopOnContainers.Services.Basket.API.Model
     public class CustomerBasket
     {
         public string BuyerId { get;  set; }
-        public List<BasketItem> Items { get; set; } 
+        public List<BasketItem> Items { get; set; } = new List<BasketItem>();
 
-        public CustomerBasket(string customerId)
-        {
+        public CustomerBasket(string customerId) =>
             BuyerId = customerId;
-            Items = new List<Model.BasketItem>();
-        }
     }
 }

src/Services/Basket/Basket.API/Model/RedisBasketRepository.cs

@@ -28,7 +28,7 @@ namespace Microsoft.eShopOnContainers.Services.Basket.API.Model
         public async Task<bool> DeleteBasket(string id)
         {
             var database = await GetDatabase();
-            return await database.KeyDeleteAsync(id.ToString());
+            return await database.KeyDeleteAsync(id);
         }
 
         public async Task<IEnumerable<string>> GetUsers()
@@ -36,11 +36,7 @@ namespace Microsoft.eShopOnContainers.Services.Basket.API.Model
             var server = await GetServer();
             
             IEnumerable<RedisKey> data = server.Keys();
-            if (data == null)
-            {
-                return null;
-            }
-            return data.Select(k => k.ToString());
+            return data?.Select(k => k.ToString());
         }
 
         public async Task<CustomerBasket> GetBasket(string customerId)
@@ -99,8 +95,6 @@ namespace Microsoft.eShopOnContainers.Services.Basket.API.Model
             _logger.LogInformation($"Connecting to database {_settings.ConnectionString} at IP {ips.First().ToString()}");
             _redis = await ConnectionMultiplexer.ConnectAsync(ips.First().ToString());
         }
-
-        
     }
 }
 

src/Services/Basket/Basket.API/Startup.cs

@@ -114,7 +114,7 @@ namespace Microsoft.eShopOnContainers.Services.Basket.API
             var identityUrl = Configuration.GetValue<string>("IdentityUrl");
             app.UseIdentityServerAuthentication(new IdentityServerAuthenticationOptions
             {
-                Authority = identityUrl.ToString(),
+                Authority = identityUrl,
                 ScopeName = "basket",
                 RequireHttpsMetadata = false
             });