fix content type negotiation test

Author: jaredcnance

src/JsonApiDotNetCore/Formatters/JsonApiOutputFormatter.cs

@@ -34,30 +34,31 @@ public async Task WriteAsync(OutputFormatterWriteContext context)
             logger?.LogInformation("Formatting response as JSONAPI");
 
             var response = context.HttpContext.Response;
-
             using (var writer = context.WriterFactory(response.Body, Encoding.UTF8))
             {
                 var jsonApiContext = GetService<IJsonApiContext>(context);
-
+                
                 string responseContent;
                 try
                 {
                     if(context.Object.GetType() == typeof(Error) || jsonApiContext.RequestEntity == null)
                     {
                         logger?.LogInformation("Response was not a JSONAPI entity. Serializing as plain JSON.");
-                        
                         responseContent = JsonConvert.SerializeObject(context.Object);
                     }
                     else
+                    {
+                        response.ContentType = "application/vnd.api+json";
                         responseContent = JsonApiSerializer.Serialize(context.Object, jsonApiContext);
+                    }
                 }
                 catch(Exception e)
                 {
                     logger?.LogError(new EventId(), e, "An error ocurred while formatting the response");
                     responseContent = new Error("400", e.Message).GetJson();
                     response.StatusCode = 400;
                 }
-
+                
                 await writer.WriteAsync(responseContent);
                 await writer.FlushAsync();       
             }

test/JsonApiDotNetCoreExampleTests/IntegrationTests/Spec/ContentNegotiation.cs

@@ -0,0 +1,44 @@
+using System.Net;
+using System.Net.Http;
+using System.Threading.Tasks;
+using DotNetCoreDocs;
+using DotNetCoreDocs.Models;
+using DotNetCoreDocs.Writers;
+using JsonApiDotNetCoreExample;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.TestHost;
+using Xunit;
+
+namespace JsonApiDotNetCoreExampleTests.IntegrationTests.Spec
+{
+    [Collection("WebHostCollection")]
+    public class ContentNegotiation
+    {
+        private DocsFixture<Startup, JsonDocWriter> _fixture;
+        public ContentNegotiation(DocsFixture<Startup, JsonDocWriter> fixture)
+        {
+            _fixture = fixture;
+        }
+
+        [Fact]
+        public async Task Server_Sends_Correct_ContentType_Header()
+        {
+            // arrange
+            var builder = new WebHostBuilder()
+                .UseStartup<Startup>();
+            var httpMethod = new HttpMethod("GET");
+            var route = "/api/v1/todo-items";
+            var description = new RequestProperties("Server Sends Correct Content Type Header");
+            var server = new TestServer(builder);
+            var client = server.CreateClient();
+            var request = new HttpRequestMessage(httpMethod, route);
+            
+            // act
+            var response = await client.SendAsync(request);
+
+            // assert
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+            Assert.Equal("application/vnd.api+json", response.Content.Headers.ContentType.ToString());
+        }
+    }
+}

test/JsonApiDotNetCoreExampleTests/IntegrationTests/TodoItemsControllerTests.cs

@@ -190,15 +190,13 @@ public async Task Can_Post_TodoItem()
 
             var request = new HttpRequestMessage(httpMethod, route);
             request.Content = new StringContent(JsonConvert.SerializeObject(content));
-            Console.WriteLine(">>>" + JsonConvert.SerializeObject(content));
             request.Content.Headers.ContentType = new MediaTypeHeaderValue("application/vnd.api+json");
 
             var description = new RequestProperties("Post TodoItem");
 
             // Act
             var response = await _fixture.MakeRequest<TodoItem>(description, request);
             var body = await response.Content.ReadAsStringAsync();
-            Console.WriteLine(">>>>>>>>" + body + response.StatusCode);
             var deserializedBody = (TodoItem)JsonApiDeSerializer.Deserialize(body, _jsonApiContext);
 
             // Assert