Call StartAsync in CompleteAsync (#24058)

src/Http/Http/src/StreamResponseBodyFeature.cs

@@ -111,7 +111,7 @@ namespace Microsoft.AspNetCore.Http
         }
 
         /// <summary>
-        /// This calls StartAsync if it has not previoulsy been called.
+        /// This calls StartAsync if it has not previously been called.
         /// It will complete the adapted pipe if it exists.
         /// </summary>
         /// <returns></returns>
@@ -128,6 +128,11 @@ namespace Microsoft.AspNetCore.Http
                 return;
             }
 
+            if (!_started)
+            {
+                await StartAsync();
+            }
+
             _completed = true;
 
             if (_pipeWriter != null)

src/Http/Http/test/Features/StreamResponseBodyFeatureTests.cs

+// 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.Buffers;
+using System.IO;
+using System.IO.Pipelines;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Http.Features
+{
+    public class StreamResponseBodyFeatureTests
+    {
+        [Fact]
+        public async Task CompleteAsyncCallsStartAsync()
+        {
+            // Arrange
+            var stream = new MemoryStream();
+            var streamResponseBodyFeature = new TestStreamResponseBodyFeature(stream);
+
+            // Act
+            await streamResponseBodyFeature.CompleteAsync();
+
+            //Assert
+            Assert.Equal(1, streamResponseBodyFeature.StartCalled);
+        }
+
+        [Fact]
+        public async Task CompleteAsyncWontCallsStartAsyncIfAlreadyStarted()
+        {
+            // Arrange
+            var stream = new MemoryStream();
+            var streamResponseBodyFeature = new TestStreamResponseBodyFeature(stream);
+            await streamResponseBodyFeature.StartAsync();
+
+            // Act
+            await streamResponseBodyFeature.CompleteAsync();
+
+            //Assert
+            Assert.Equal(1, streamResponseBodyFeature.StartCalled);
+        }
+    }
+
+    public class TestStreamResponseBodyFeature : StreamResponseBodyFeature
+    {
+        public TestStreamResponseBodyFeature(Stream stream)
+            : base(stream)
+        {
+
+        }
+
+        public override Task StartAsync(CancellationToken cancellationToken = default)
+        {
+            StartCalled++;
+            return base.StartAsync(cancellationToken);
+        }
+
+        public int StartCalled { get; private set; }
+    }
+}