Set IExceptionHandlerFeature on DeveloperExceptionPageMiddleware

src/Middleware/Diagnostics/src/DeveloperExceptionPage/DeveloperExceptionPageMiddlewareImpl.cs

@@ -148,7 +148,10 @@ public async Task Invoke(HttpContext context)
                     context.Response.StatusCode = 500;
                 }
 
-                await _exceptionHandler(new ErrorContext(context, ex));
+                var errorContext = new ErrorContext(context, ex);
+
+                SetExceptionHandlerFeatures(errorContext);
+                await _exceptionHandler(errorContext);
 
                 const string eventName = "Microsoft.AspNetCore.Diagnostics.UnhandledException";
                 if (_diagnosticSource.IsEnabled(eventName))
@@ -200,17 +203,12 @@ private async Task DisplayExceptionContent(ErrorContext errorContext)
     {
         var httpContext = errorContext.HttpContext;
 
-        if (_problemDetailsService is not null)
-        {
-            SetExceptionHandlerFeatures(errorContext);
-        }
-
         if (_problemDetailsService == null || !await _problemDetailsService.TryWriteAsync(new()
-            {
-                HttpContext = httpContext,
-                ProblemDetails = CreateProblemDetails(errorContext, httpContext), 
-                Exception = errorContext.Exception 
-            }))
+        {
+            HttpContext = httpContext,
+            ProblemDetails = CreateProblemDetails(errorContext, httpContext),
+            Exception = errorContext.Exception
+        }))
         {
             httpContext.Response.ContentType = "text/plain; charset=utf-8";
 

src/Middleware/Diagnostics/test/UnitTests/ExceptionHandlerMiddlewareTest.cs

@@ -315,6 +315,51 @@ public async Task Metrics_ExceptionThrown_Unhandled_Reported()
             m => AssertRequestException(m, "System.InvalidOperationException", "unhandled"));
     }
 
+    [Fact]
+    public async Task ExceptionFeatureSetOnDeveloperExceptionPage()
+    {
+        // Arrange
+        var tcs = new TaskCompletionSource<IExceptionHandlerPathFeature>(TaskCreationOptions.RunContinuationsAsynchronously);
+
+        using var host = new HostBuilder()
+            .ConfigureWebHost(webHostBuilder =>
+            {
+                webHostBuilder
+                .UseTestServer()
+                .Configure(app =>
+                {
+                    app.Use(async (context, next) =>
+                    {
+                        await next();
+
+                        var exceptionHandlerFeature = context.Features.GetRequiredFeature<IExceptionHandlerPathFeature>();
+                        tcs.SetResult(exceptionHandlerFeature);
+                    });
+                    app.UseExceptionHandler(exceptionApp =>
+                    {
+                        exceptionApp.Run(context => Task.CompletedTask);
+                    });
+                    app.Run(context =>
+                    {
+                        throw new Exception("Test exception");
+                    });
+
+                });
+            }).Build();
+
+        await host.StartAsync();
+
+        var server = host.GetTestServer();
+        var request = new HttpRequestMessage(HttpMethod.Get, "/path");
+
+        var response = await server.CreateClient().SendAsync(request);
+
+        var feature = await tcs.Task;
+        Assert.NotNull(feature);
+        Assert.Equal("Test exception", feature.Error.Message);
+        Assert.Equal("/path", feature.Path);
+    }
+
     private static void AssertRequestException(CollectedMeasurement<long> measurement, string exceptionName, string result, string handler = null)
     {
         Assert.Equal(1, measurement.Value);