Connect module exception handling to HttpContext

src/Microsoft.AspNetCore.SystemWebAdapters.CoreServices/HttpApplication/HttpApplicationMiddleware.cs

@@ -28,6 +28,7 @@ public async Task InvokeAsync(HttpContextCore context)
 
         context.Features.Set<IHttpApplicationFeature>(httpApplicationFeature);
         context.Features.Set<IHttpResponseEndFeature>(httpApplicationFeature);
+        context.Features.Set<IRequestExceptionFeature>(httpApplicationFeature);
 
         try
         {
@@ -48,6 +49,7 @@ public async Task InvokeAsync(HttpContextCore context)
         {
             context.Features.Set<IHttpResponseEndFeature>(endFeature);
             context.Features.Set<IHttpApplicationFeature>(null);
+            context.Features.Set<IRequestExceptionFeature>(null);
 
             _pool.Return(app);
         }

src/Microsoft.AspNetCore.SystemWebAdapters.CoreServices/HttpApplication/RequestHttpApplicationFeature.cs

@@ -8,7 +8,7 @@
 
 namespace Microsoft.AspNetCore.SystemWebAdapters;
 
-internal sealed class RequestHttpApplicationFeature : IHttpApplicationFeature, IHttpResponseEndFeature
+internal sealed class RequestHttpApplicationFeature : IHttpApplicationFeature, IHttpResponseEndFeature, IRequestExceptionFeature
 {
     private readonly IHttpResponseEndFeature _previous;
     private List<Exception>? _exceptions;
@@ -33,7 +33,7 @@ ValueTask IHttpApplicationFeature.RaiseEventAsync(ApplicationEvent @event)
         return ValueTask.CompletedTask;
     }
 
-    [System.Diagnostics.CodeAnalysis.SuppressMessage("Design", "CA1031:Do not catch general exception types", Justification = "Need to handle all exceptions")]
+    [System.Diagnostics.CodeAnalysis.SuppressMessage("Design", "CA1031:Do not catch general exception types", Justification = "Must handle all exceptions here")]
     private void RaiseEvent(ApplicationEvent appEvent, bool suppressThrow)
     {
         (CurrentNotification, IsPostNotification) = appEvent switch
@@ -111,4 +111,11 @@ async Task IHttpResponseEndFeature.EndAsync()
     }
 
     private void AddError(Exception ex) => (_exceptions ??= new()).Add(ex);
+
+    void IRequestExceptionFeature.Add(Exception exception) => AddError(exception);
+
+    IReadOnlyList<Exception> IRequestExceptionFeature.Exceptions
+        => ((IReadOnlyList<Exception>?)_exceptions) ?? Array.Empty<Exception>();
+
+    void IRequestExceptionFeature.Clear() => _exceptions = null;
 }

src/Microsoft.AspNetCore.SystemWebAdapters/Adapters/IRequestExceptionFeature.cs

@@ -0,0 +1,18 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#if NET6_0_OR_GREATER
+using System;
+using System.Collections.Generic;
+
+namespace Microsoft.AspNetCore.SystemWebAdapters;
+
+internal interface IRequestExceptionFeature
+{
+    IReadOnlyList<Exception> Exceptions { get; }
+
+    void Add(Exception exception);
+
+    void Clear();
+}
+#endif

src/Microsoft.AspNetCore.SystemWebAdapters/Generated/Ref.Standard.cs

@@ -105,11 +105,13 @@ public partial class HttpBrowserCapabilitiesWrapper : System.Web.HttpBrowserCapa
     public partial class HttpContext : System.IServiceProvider
     {
         internal HttpContext() { }
+        public System.Exception[] AllErrors { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public System.Web.HttpApplicationState Application { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public System.Web.HttpApplication ApplicationInstance { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public System.Web.Caching.Cache Cache { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public static System.Web.HttpContext Current { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public System.Web.RequestNotification CurrentNotification { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public System.Exception Error { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public bool IsDebuggingEnabled { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public bool IsPostNotification { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public System.Collections.IDictionary Items { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
@@ -119,6 +121,7 @@ internal HttpContext() { }
         public System.Web.SessionState.HttpSessionState Session { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public System.DateTime Timestamp { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public System.Security.Principal.IPrincipal User { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} set { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public void AddError(System.Exception ex) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
         public void ClearError() { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
         public System.Web.ISubscriptionToken DisposeOnPipelineCompleted(System.IDisposable target) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
         public void RewritePath(string path) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
@@ -127,10 +130,12 @@ internal HttpContext() { }
     public partial class HttpContextBase : System.IServiceProvider
     {
         protected HttpContextBase() { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
+        public virtual System.Exception[] AllErrors { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public virtual System.Web.HttpApplicationState Application { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public virtual System.Web.HttpApplication ApplicationInstance { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public virtual System.Web.Caching.Cache Cache { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public virtual System.Web.RequestNotification CurrentNotification { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public virtual System.Exception Error { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public virtual bool IsDebuggingEnabled { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public virtual bool IsPostNotification { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public virtual System.Collections.IDictionary Items { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
@@ -140,15 +145,19 @@ public partial class HttpContextBase : System.IServiceProvider
         public virtual System.Web.HttpSessionStateBase Session { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public virtual System.DateTime Timestamp { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public virtual System.Security.Principal.IPrincipal User { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} set { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public virtual void AddError(System.Exception ex) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
+        public virtual void ClearError() { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
         public virtual object GetService(System.Type serviceType) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
     }
     public partial class HttpContextWrapper : System.Web.HttpContextBase
     {
         public HttpContextWrapper(System.Web.HttpContext httpContext) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
+        public override System.Exception[] AllErrors { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public override System.Web.HttpApplicationState Application { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public override System.Web.HttpApplication ApplicationInstance { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public override System.Web.Caching.Cache Cache { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public override System.Web.RequestNotification CurrentNotification { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public override System.Exception Error { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public override bool IsDebuggingEnabled { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public override bool IsPostNotification { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public override System.Collections.IDictionary Items { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
@@ -158,6 +167,8 @@ public partial class HttpContextWrapper : System.Web.HttpContextBase
         public override System.Web.HttpSessionStateBase Session { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public override System.DateTime Timestamp { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public override System.Security.Principal.IPrincipal User { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} set { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public override void AddError(System.Exception ex) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
+        public override void ClearError() { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
     }
     public sealed partial class HttpCookie
     {

src/Microsoft.AspNetCore.SystemWebAdapters/HttpContext.cs

@@ -3,6 +3,7 @@
 
 using System.Collections;
 using System.Diagnostics.CodeAnalysis;
+using System.Linq;
 using System.Security.Claims;
 using System.Security.Principal;
 using System.Web.Caching;
@@ -41,6 +42,15 @@ internal HttpContext(HttpContextCore context)
 
     public HttpServerUtility Server => _server ??= new(_context);
 
+    public Exception? Error => _context.Features.Get<IRequestExceptionFeature>()?.Exceptions is [{ } error, ..] ? error : null;
+
+    [SuppressMessage("Performance", "CA1819:Properties should not return arrays", Justification = Constants.ApiFromAspNet)]
+    public Exception[] AllErrors => _context.Features.Get<IRequestExceptionFeature>()?.Exceptions.ToArray() ?? Array.Empty<Exception>();
+
+    public void ClearError() => _context.Features.Get<IRequestExceptionFeature>()?.Clear();
+
+    public void AddError(Exception ex) => _context.Features.Get<IRequestExceptionFeature>()?.Add(ex);
+
     public RequestNotification CurrentNotification => _context.Features.GetRequired<IHttpApplicationFeature>().CurrentNotification;
 
     public bool IsPostNotification => _context.Features.GetRequired<IHttpApplicationFeature>().IsPostNotification;
@@ -64,12 +74,6 @@ public IPrincipal User
 
     public HttpSessionState? Session => _context.Features.Get<HttpSessionState>();
 
-    [SuppressMessage("Performance", "CA1822:Mark members as static", Justification = Constants.ApiFromAspNet)]
-    public void ClearError()
-    {
-        // Intentionally implemented without any behavior as there's nothing equivalent in ASP.NET Core
-    }
-
     public DateTime Timestamp { get; } = DateTime.UtcNow.ToLocalTime();
 
     public void RewritePath(string path)

src/Microsoft.AspNetCore.SystemWebAdapters/HttpContextBase.cs

@@ -19,6 +19,16 @@ protected HttpContextBase()
 
         public virtual HttpResponseBase Response => throw new NotImplementedException();
 
+        [SuppressMessage("Naming", "CA1716:Identifiers should not match keywords", Justification = Constants.ApiFromAspNet)]
+        public virtual Exception? Error => throw new NotImplementedException();
+
+        [SuppressMessage("Performance", "CA1819:Properties should not return arrays", Justification = Constants.ApiFromAspNet)]
+        public virtual Exception[] AllErrors => throw new NotImplementedException();
+
+        public virtual void ClearError() => throw new NotImplementedException();
+
+        public virtual void AddError(Exception ex) => throw new NotImplementedException();
+
         public virtual HttpApplication ApplicationInstance => throw new NotImplementedException();
 
         public virtual HttpApplicationState Application => throw new NotImplementedException();

src/Microsoft.AspNetCore.SystemWebAdapters/HttpContextWrapper.cs

@@ -29,6 +29,14 @@ public HttpContextWrapper(HttpContext httpContext)
 
         public override bool IsDebuggingEnabled => _context.IsDebuggingEnabled;
 
+        public override void AddError(Exception ex) => _context.AddError(ex);
+
+        public override Exception[] AllErrors => _context.AllErrors;
+
+        public override void ClearError() => _context.ClearError();
+
+        public override Exception? Error => _context.Error;
+
         public override HttpRequestBase Request => _request ??= new HttpRequestWrapper(_context.Request);
 
         public override HttpResponseBase Response => _response ??= new HttpResponseWrapper(_context.Response);

src/Microsoft.AspNetCore.SystemWebAdapters/HttpServerUtility.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.IO;
+using System.Linq;
 using Microsoft.AspNetCore.SystemWebAdapters;
 using Microsoft.AspNetCore.WebUtilities;
 using Microsoft.Extensions.DependencyInjection;
@@ -42,12 +43,9 @@ public string MapPath(string? path)
             .TrimEnd(Path.DirectorySeparatorChar);
     }
 
-    [Diagnostics.CodeAnalysis.SuppressMessage("Design", "CA1024:Use properties where appropriate", Justification = Constants.ApiFromAspNet)]
-    public Exception? GetLastError() => null;
+    public Exception? GetLastError() => _context.GetAdapter().Error;
 
-    public void ClearError()
-    {
-    }
+    public void ClearError() => _context.GetAdapter().ClearError();
 
     /// <summary>
     /// This method is similar to <see cref="WebEncoders.Base64UrlDecode(string)"/> but handles the trailing character that <see cref="UrlTokenEncode(byte[])"/>

test/Microsoft.AspNetCore.SystemWebAdapters.Tests/HttpContextTests.cs

@@ -243,6 +243,99 @@ public void DisposeOnPipelineCompletedDisposed()
             disposable.Verify(d => d.Dispose(), Times.Once);
         }
 
+        [Fact]
+        public void ErrorNoFeature()
+        {
+            // Arrange
+            var context = new HttpContext(new DefaultHttpContext());
+
+            // Assert
+            var error = context.Error;
+            var allErrors = context.AllErrors;
+
+            // No ops
+            context.ClearError();
+            context.AddError(new InvalidOperationException());
+
+            // Assert
+            Assert.Null(error);
+            Assert.Empty(allErrors);
+        }
+
+        [InlineData(0)]
+        [InlineData(1)]
+        [InlineData(2)]
+        [Theory]
+        public void ErrorWithFeatureGet(int length)
+        {
+            // Arrange
+            var coreContext = new DefaultHttpContext();
+            var context = new HttpContext(coreContext);
+
+            var exceptionFeature = new Mock<IRequestExceptionFeature>();
+            var errors = new List<Exception>();
+
+            for (var i = 0; i < length; i++)
+            {
+                errors.Add(new Mock<Exception>().Object);
+            }
+
+            exceptionFeature.Setup(f => f.Exceptions).Returns(errors);
+            coreContext.Features.Set(exceptionFeature.Object);
+
+            // Act
+            var error = context.Error;
+            var allErrors = context.AllErrors;
+
+            // Assert
+            Assert.Equal(allErrors, errors);
+            Assert.NotSame(allErrors, errors);
+
+            if (length > 0)
+            {
+                Assert.Same(error, errors[0]);
+            }
+            else
+            {
+                Assert.Null(error);
+            }
+        }
+
+        [Fact]
+        public void ErrorWithFeatureClear()
+        {
+            // Arrange
+            var coreContext = new DefaultHttpContext();
+            var context = new HttpContext(coreContext);
+
+            var exceptionFeature = new Mock<IRequestExceptionFeature>();
+            coreContext.Features.Set(exceptionFeature.Object);
+
+            // Act
+            context.ClearError();
+
+            // Assert
+            exceptionFeature.Verify(f => f.Clear(), Times.Once);
+        }
+
+        [Fact]
+        public void ErrorWithFeatureAdd()
+        {
+            // Arrange
+            var coreContext = new DefaultHttpContext();
+            var context = new HttpContext(coreContext);
+
+            var error = new InvalidOperationException();
+            var exceptionFeature = new Mock<IRequestExceptionFeature>();
+            coreContext.Features.Set(exceptionFeature.Object);
+
+            // Act
+            context.AddError(error);
+
+            // Assert
+            exceptionFeature.Verify(f => f.Add(error), Times.Once);
+        }
+
         [InlineData("path1", "/path1", "", 0)]
         [InlineData("/path1", "/path1", "", 0)]
         [InlineData("path1?", "/path1", "", 0)]