src/CleanArchitecture.Web/Api/ToDoItemsController.cs

@@ -50,6 +50,7 @@ namespace CleanArchitecture.Web.Api
         public IActionResult MarkComplete(int itemId)
         {
             var item = _todoRepository.GetById(itemId);
+            if (item == null) return NotFound();
             item.MarkComplete();
             _todoRepository.Update(item);
 

tests/CleanArchitecture.Tests/Integration/Web/ApiToDoItemsControllerListShould.cs

 using CleanArchitecture.Core.Entities;
-using CleanArchitecture.Web;
-using Microsoft.AspNetCore.Hosting;
-using Microsoft.AspNetCore.TestHost;
 using Newtonsoft.Json;
 using System.Collections.Generic;
-using System.IO;
 using System.Linq;
-using System.Net.Http;
-using System.Net.Http.Headers;
 using System.Threading.Tasks;
 using Xunit;
 
@@ -22,7 +16,7 @@ namespace CleanArchitecture.Tests.Integration.Web
             var response = await _client.GetAsync("/api/todoitems");
             response.EnsureSuccessStatusCode();
             var stringResponse = await response.Content.ReadAsStringAsync();
-            var result = JsonConvert.DeserializeObject<IEnumerable<ToDoItem>>(stringResponse).ToList();
+            var result = JsonConvert.DeserializeObject<IEnumerable<ToDoItem>>(stringResponse);
 
             Assert.Equal(2, result.Count());
             Assert.Equal(1, result.Count(a => a.Title == "Test Item 1"));

tests/CleanArchitecture.Tests/Integration/Web/BaseWebTest.cs

@@ -33,9 +33,7 @@ namespace CleanArchitecture.Tests.Integration.Web
                 .UseEnvironment("Testing"); // ensure ConfigureTesting is called in Startup
 
             var server = new TestServer(builder);
-            var client = server.CreateClient();
-
-            return client;
+            return server.CreateClient();
         }
 
         protected virtual void InitializeServices(IServiceCollection services)