Handle synchronous exceptions from partial (#16679)

Handle sync exceptions within async context

Author: ryanbrandenburg

src/Mvc/Mvc.Core/src/Infrastructure/ContentResultExecutor.cs

@@ -55,7 +55,7 @@ public virtual async Task ExecuteAsync(ActionContext context, ContentResult resu
             {
                 response.ContentLength = resolvedContentTypeEncoding.GetByteCount(result.Content);
 
-                using (var textWriter = _httpResponseStreamWriterFactory.CreateWriter(response.Body, resolvedContentTypeEncoding))
+                await using (var textWriter = _httpResponseStreamWriterFactory.CreateWriter(response.Body, resolvedContentTypeEncoding))
                 {
                     await textWriter.WriteAsync(result.Content);
 

src/Mvc/Mvc.Razor/src/RazorView.cs

@@ -286,7 +286,7 @@ private async Task RenderLayoutAsync(
             {
                 // This means we're writing to a 'real' writer, probably to the actual output stream.
                 // We're using PagedBufferedTextWriter here to 'smooth' synchronous writes of IHtmlContent values.
-                using (var writer = _bufferScope.CreateWriter(context.Writer))
+                await using (var writer = _bufferScope.CreateWriter(context.Writer))
                 {
                     await bodyWriter.Buffer.WriteToAsync(writer, _htmlEncoder);
                     await writer.FlushAsync();

src/Mvc/Mvc.ViewFeatures/src/ViewComponentResultExecutor.cs

@@ -123,7 +123,7 @@ public virtual async Task ExecuteAsync(ActionContext context, ViewComponentResul
 
             _writerFactory ??= context.HttpContext.RequestServices.GetRequiredService<IHttpResponseStreamWriterFactory>();
 
-            using (var writer = _writerFactory.CreateWriter(response.Body, resolvedContentTypeEncoding))
+            await using (var writer = _writerFactory.CreateWriter(response.Body, resolvedContentTypeEncoding))
             {
                 var viewContext = new ViewContext(
                     context,
@@ -149,8 +149,8 @@ public virtual async Task ExecuteAsync(ActionContext context, ViewComponentResul
                 }
                 else
                 {
-                    using var bufferingStream = new FileBufferingWriteStream();
-                    using (var intermediateWriter = _writerFactory.CreateWriter(bufferingStream, resolvedContentTypeEncoding))
+                    await using var bufferingStream = new FileBufferingWriteStream();
+                    await using (var intermediateWriter = _writerFactory.CreateWriter(bufferingStream, resolvedContentTypeEncoding))
                     {
                         viewComponentResult.WriteTo(intermediateWriter, _htmlEncoder);
                     }

src/Mvc/Mvc.ViewFeatures/src/ViewExecutor.cs

@@ -233,7 +233,7 @@ protected async Task ExecuteAsync(
 
             OnExecuting(viewContext);
 
-            using (var writer = WriterFactory.CreateWriter(response.Body, resolvedContentTypeEncoding))
+            await using (var writer = WriterFactory.CreateWriter(response.Body, resolvedContentTypeEncoding))
             {
                 var view = viewContext.View;
 

src/Mvc/Mvc.ViewFeatures/test/ViewExecutorTest.cs

@@ -83,6 +83,44 @@ public static TheoryData<MediaTypeHeaderValue, string, string> ViewExecutorSetsC
             }
         }
 
+        [Fact]
+        public async Task ExecuteAsync_ExceptionInSyncContext()
+        {
+            // Arrange
+            var view = CreateView((v) =>
+            {
+                v.Writer.Write("xyz");
+                throw new NotImplementedException("This should be raw!");
+            });
+
+            var context = new DefaultHttpContext();
+            var stream = new Mock<Stream>();
+            stream.Setup(s => s.CanWrite).Returns(true);
+
+            context.Response.Body = stream.Object;
+            var actionContext = new ActionContext(
+                context,
+                new RouteData(),
+                new ActionDescriptor());
+            var viewData = new ViewDataDictionary(new EmptyModelMetadataProvider());
+
+            var viewExecutor = CreateViewExecutor();
+
+            // Act
+            var exception = await Assert.ThrowsAsync<NotImplementedException>(async () => await viewExecutor.ExecuteAsync(
+                actionContext,
+                view,
+                viewData,
+                Mock.Of<ITempDataDictionary>(),
+                contentType: null,
+                statusCode: null)
+            );
+
+            // Assert
+            Assert.Equal("This should be raw!", exception.Message);
+            stream.Verify(s => s.Write(It.IsAny<byte[]>(), It.IsAny<int>(), It.IsAny<int>()), Times.Never);
+        }
+
         [Theory]
         [MemberData(nameof(ViewExecutorSetsContentTypeAndEncodingData))]
         public async Task ExecuteAsync_SetsContentTypeAndEncoding(

src/Mvc/test/Mvc.FunctionalTests/TagHelpersTest.cs

@@ -64,6 +64,17 @@ public async Task CanRenderViewsWithTagHelpers(string action)
 #endif
         }
 
+        [Fact]
+        public async Task GivesCorrectCallstackForSyncronousCalls()
+        {
+            // Regression test for https://github.com/aspnet/AspNetCore/issues/15367
+            // Arrange
+            var exception = await Assert.ThrowsAsync<HttpRequestException>(async () => await Client.GetAsync("http://localhost/Home/MyHtml"));
+
+            // Assert
+            Assert.Equal("Should be visible", exception.InnerException.InnerException.Message);
+        }
+
         [Fact]
         public async Task CanRenderViewsWithTagHelpersAndUnboundDynamicAttributes_Encoded()
         {
@@ -318,4 +329,4 @@ public async Task EncodersPages_ReturnExpectedContent(string actionName)
 #endif
         }
     }
-}
+}

src/Mvc/test/WebSites/TagHelpersWebSite/Controllers/HomeController.cs

@@ -35,6 +35,11 @@ public IActionResult Help()
             return View();
         }
 
+        public IActionResult MyHtml()
+        {
+            return View();
+        }
+
         public IActionResult ViewComponentTagHelpers()
         {
             return View();

src/Mvc/test/WebSites/TagHelpersWebSite/MyHtmlContent.cs

@@ -0,0 +1,27 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.IO;
+using System.Text.Encodings.Web;
+using Microsoft.AspNetCore.Html;
+using Microsoft.AspNetCore.Mvc.Rendering;
+
+namespace TagHelpersWebSite
+{
+    public class MyHtmlContent : IHtmlContent
+    {
+        private IHtmlHelper Html { get; }
+
+        public MyHtmlContent(IHtmlHelper html)
+        {
+            Html = html;
+        }
+
+        public void WriteTo(TextWriter writer, HtmlEncoder encoder)
+        {
+#pragma warning disable MVC1000 // Use of IHtmlHelper.{0} should be avoided.
+            Html.Partial("_Test").WriteTo(writer, encoder);
+#pragma warning restore MVC1000 // Use of IHtmlHelper.{0} should be avoided.
+        }
+    }
+}

src/Mvc/test/WebSites/TagHelpersWebSite/Startup.cs

@@ -3,6 +3,7 @@
 
 using System.IO;
 using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Diagnostics;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.DependencyInjection;

src/Mvc/test/WebSites/TagHelpersWebSite/TagHelpersWebSite.csproj

@@ -9,7 +9,7 @@
   <ItemGroup>
     <ProjectReference Include="..\RazorPagesClassLibrary\RazorPagesClassLibrary.csproj" />
   </ItemGroup>
-  
+
   <ItemGroup>
     <Reference Include="Microsoft.AspNetCore.Mvc" />
     <Reference Include="Microsoft.AspNetCore.Server.IISIntegration" />

src/Mvc/test/WebSites/TagHelpersWebSite/Views/Home/MyHtml.cshtml

@@ -0,0 +1 @@
+@(new TagHelpersWebSite.MyHtmlContent(Html))

src/Mvc/test/WebSites/TagHelpersWebSite/Views/Home/_Test.cshtml

@@ -0,0 +1,3 @@
+@{
+    throw new Exception("Should be visible");
+}