Fix issue #1280 - Add HttpResponseMessageFormatter

Adds a formatter that can convert an HttpResponseMessage returned from an
action into HttpContext.Response output.

Author: rynowak

src/Microsoft.AspNet.Mvc.WebApiCompatShim/Formatters/HttpResponseMessageOutputFormatter.cs

@@ -0,0 +1,65 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net.Http;
+using System.Threading.Tasks;
+using Microsoft.AspNet.Mvc.HeaderValueAbstractions;
+
+namespace Microsoft.AspNet.Mvc.WebApiCompatShim
+{
+    public class HttpResponseMessageOutputFormatter : IOutputFormatter
+    {
+        public bool CanWriteResult(OutputFormatterContext context, MediaTypeHeaderValue contentType)
+        {
+            return context.Object is HttpResponseMessage;
+        }
+
+        public IReadOnlyList<MediaTypeHeaderValue> GetSupportedContentTypes(
+            Type declaredType, 
+            Type runtimeType, 
+            MediaTypeHeaderValue contentType)
+        {
+            return null;
+        }
+
+        public async Task WriteAsync(OutputFormatterContext context)
+        {
+            var liveResponse = context.ActionContext.HttpContext.Response;
+
+            var response = context.Object as HttpResponseMessage;
+            if (response == null)
+            {
+                var message = Resources.FormatHttpResponseMessageFormatter_UnsupportedType(
+                    nameof(HttpResponseMessageOutputFormatter), 
+                    nameof(HttpResponseMessage));
+
+                throw new InvalidOperationException(message);
+            }
+
+            var contentHeaders = response.Content?.Headers;
+            if (contentHeaders != null)
+            {
+                foreach (var header in contentHeaders)
+                {
+                    liveResponse.Headers.AppendValues(header.Key, header.Value.ToArray());
+                }
+            }
+
+            var resonseHeaders = response.Headers;
+            foreach (var header in resonseHeaders)
+            {
+                liveResponse.Headers.AppendValues(header.Key, header.Value.ToArray());
+            }
+
+            liveResponse.StatusCode = (int)response.StatusCode;
+
+            if (response.Content != null)
+            {
+                await response.Content.CopyToAsync(liveResponse.Body);
+            }
+        }
+    }
+}

src/Microsoft.AspNet.Mvc.WebApiCompatShim/Properties/Resources.Designer.cs

@@ -117,6 +117,9 @@
   <resheader name="writer">
     <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
   </resheader>
+  <data name="HttpResponseMessageFormatter_UnsupportedType" xml:space="preserve">
+    <value>The {0} only supports writing objects of type {1}.</value>
+  </data>
   <data name="JQuerySyntaxMissingClosingBracket" xml:space="preserve">
     <value>The key is invalid JQuery syntax because it is missing a closing bracket.</value>
   </data>

src/Microsoft.AspNet.Mvc.WebApiCompatShim/Resources.resx

@@ -24,6 +24,9 @@ public void Invoke(MvcOptions options)
 
             // Add a model binder to be able to bind HttpRequestMessage
             options.ModelBinders.Insert(0, new HttpRequestMessageModelBinder());
+
+            // Add a formatter to write out an HttpResponseMessage to the response
+            options.OutputFormatters.Add(new HttpResponseMessageOutputFormatter());
         }
 
         public void Invoke(WebApiCompatShimOptions options)

src/Microsoft.AspNet.Mvc.WebApiCompatShim/WebApiCompatShimOptionsSetup.cs

@@ -11,6 +11,7 @@
 using Microsoft.AspNet.TestHost;
 using Newtonsoft.Json;
 using Xunit;
+using System.Collections.Generic;
 
 namespace Microsoft.AspNet.Mvc.FunctionalTests
 {
@@ -123,6 +124,58 @@ public async Task ApiController_RequestParameter()
             Assert.Equal(HttpStatusCode.OK, response.StatusCode);
             Assert.Equal(expected, content);
         }
+
+        [Fact]
+        public async Task ApiController_ResponseReturned()
+        {
+            // Arrange
+            var server = TestServer.Create(_provider, _app);
+            var client = server.CreateClient();
+
+            var expected =
+                "POST Hello, HttpResponseMessage world!";
+
+            // Act
+            var response = await client.PostAsync(
+                "http://localhost/api/Blog/HttpRequestMessage/EchoWithResponseMessage",
+                new StringContent("Hello, HttpResponseMessage world!"));
+            var content = await response.Content.ReadAsStringAsync();
+
+            // Assert
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+            Assert.Equal(expected, content);
+
+            IEnumerable<string> values;
+            Assert.True(response.Headers.TryGetValues("X-Test", out values));
+            Assert.Equal(new string[] { "Hello!" }, values);
+            Assert.Equal(38, response.Content.Headers.ContentLength);
+        }
+
+        [Fact]
+        public async Task ApiController_ResponseReturned_Chunked()
+        {
+            // Arrange
+            var server = TestServer.Create(_provider, _app);
+            var client = server.CreateClient();
+
+            var expected =
+                "POST Hello, HttpResponseMessage world!";
+
+            // Act
+            var response = await client.PostAsync(
+                "http://localhost/api/Blog/HttpRequestMessage/EchoWithResponseMessageChunked",
+                new StringContent("Hello, HttpResponseMessage world!"));
+            var content = await response.Content.ReadAsStringAsync();
+
+            // Assert
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+            Assert.Equal(expected, content);
+
+            IEnumerable<string> values;
+            Assert.True(response.Headers.TryGetValues("X-Test", out values));
+            Assert.Equal(new string[] { "Hello!" }, values);
+            Assert.Equal(true, response.Headers.TransferEncodingChunked);
+        }
     }
 }
 #endif

test/Microsoft.AspNet.Mvc.FunctionalTests/WebApiCompatShimBasicTest.cs

@@ -7,6 +7,7 @@
 using System.Web.Http;
 using Microsoft.AspNet.Http;
 using Microsoft.AspNet.Mvc;
+using System.Net;
 
 namespace WebApiCompatShimWebSite
 {
@@ -29,6 +30,33 @@ public async Task<IActionResult> EchoParameter(HttpRequestMessage request)
             return new EmptyResult();
         }
 
+        public async Task<HttpResponseMessage> EchoWithResponseMessage(HttpRequestMessage request)
+        {
+            var message = string.Format(
+                "{0} {1}", 
+                request.Method.ToString(), 
+                await request.Content.ReadAsStringAsync());
+
+            var response = request.CreateResponse(HttpStatusCode.OK);
+            response.Content = new StringContent(message);
+            response.Headers.TryAddWithoutValidation("X-Test", "Hello!");
+            return response;
+        }
+
+        public async Task<HttpResponseMessage> EchoWithResponseMessageChunked(HttpRequestMessage request)
+        {
+            var message = string.Format(
+                "{0} {1}",
+                request.Method.ToString(),
+                await request.Content.ReadAsStringAsync());
+
+            var response = request.CreateResponse(HttpStatusCode.OK);
+            response.Content = new StringContent(message);
+            response.Headers.TransferEncodingChunked = true;
+            response.Headers.TryAddWithoutValidation("X-Test", "Hello!");
+            return response;
+        }
+
         private async Task Echo(HttpRequestMessage request)
         {
             var message = string.Format(