[Fixes #3274] Added DiagnosticsSource for ViewComponent

src/Microsoft.AspNet.Mvc.ViewFeatures/DiagnosticSource/ViewComponentDiagnosticSourceExtensions.cs

@@ -0,0 +1,87 @@
+// 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.Diagnostics;
+using Microsoft.AspNet.Mvc.Abstractions;
+using Microsoft.AspNet.Mvc.ViewComponents;
+using Microsoft.AspNet.Mvc.ViewEngines;
+
+namespace Microsoft.AspNet.Mvc.Diagnostics
+{
+    public static class ViewComponentDiagnosticSourceExtensions
+    {
+        public static void BeforeViewComponent(
+            this DiagnosticSource diagnosticSource,
+            ViewComponentContext context,
+            object viewComponent)
+        {
+            if (diagnosticSource.IsEnabled("Microsoft.AspNet.Mvc.BeforeViewComponent"))
+            {
+                diagnosticSource.Write(
+                "Microsoft.AspNet.Mvc.BeforeViewComponent",
+                new
+                {
+                    actionDescriptor = context.ViewContext.ActionDescriptor,
+                    viewComponentContext = context,
+                    viewComponent = viewComponent
+                });
+            }
+        }
+
+        public static void AfterViewComponent(
+            this DiagnosticSource diagnosticSource,
+            ViewComponentContext context,
+            IViewComponentResult result,
+            object viewComponent)
+        {
+            if (diagnosticSource.IsEnabled("Microsoft.AspNet.Mvc.AfterViewComponent"))
+            {
+                diagnosticSource.Write(
+                "Microsoft.AspNet.Mvc.AfterViewComponent",
+                new
+                {
+                    actionDescriptor = context.ViewContext.ActionDescriptor,
+                    viewComponentContext = context,
+                    viewComponentResult = result,
+                    viewComponent = viewComponent
+                });
+            }
+        }
+
+        public static void ViewComponentBeforeViewExecute(
+            this DiagnosticSource diagnosticSource,
+            ViewComponentContext context,
+            IView view)
+        {
+            if (diagnosticSource.IsEnabled("Microsoft.AspNet.Mvc.ViewComponentBeforeViewExecute"))
+            {
+                diagnosticSource.Write(
+                    "Microsoft.AspNet.Mvc.ViewComponentBeforeViewExecute",
+                    new
+                    {
+                        actionDescriptor = context.ViewContext.ActionDescriptor,
+                        viewComponentContext = context,
+                        view = view
+                    });
+            }
+        }
+
+        public static void ViewComponentAfterViewExecute(
+            this DiagnosticSource diagnosticSource,
+            ViewComponentContext context,
+            IView view)
+        {
+            if (diagnosticSource.IsEnabled("Microsoft.AspNet.Mvc.ViewComponentAfterViewExecute"))
+            {
+                diagnosticSource.Write(
+                    "Microsoft.AspNet.Mvc.ViewComponentAfterViewExecute",
+                    new
+                    {
+                        actionDescriptor = context.ViewContext.ActionDescriptor,
+                        viewComponentContext = context,
+                        view = view
+                    });
+            }
+        }
+    }
+}

src/Microsoft.AspNet.Mvc.ViewFeatures/DiagnosticSource/ViewExecutorDiagnosticSourceExtensions.cs

@@ -0,0 +1,85 @@
+// 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.Collections.Generic;
+using System.Diagnostics;
+using Microsoft.AspNet.Mvc.Rendering;
+using Microsoft.AspNet.Mvc.ViewEngines;
+
+namespace Microsoft.AspNet.Mvc.Diagnostics
+{
+    public static class ViewExecutorDiagnosticSourceExtensions
+    {
+        public static void BeforeView(
+            this DiagnosticSource diagnosticSource,
+            IView view,
+            ViewContext viewContext)
+        {
+            if (diagnosticSource.IsEnabled("Microsoft.AspNet.Mvc.BeforeView"))
+            {
+                diagnosticSource.Write(
+                    "Microsoft.AspNet.Mvc.BeforeView",
+                    new { view = view, viewContext = viewContext, });
+            }
+        }
+
+        public static void AfterView(
+            this DiagnosticSource diagnosticSource,
+            IView view,
+            ViewContext viewContext)
+        {
+            if (diagnosticSource.IsEnabled("Microsoft.AspNet.Mvc.AfterView"))
+            {
+                diagnosticSource.Write(
+                    "Microsoft.AspNet.Mvc.AfterView",
+                    new { view = view, viewContext = viewContext, });
+            }
+        }
+
+        public static void ViewFound(
+            this DiagnosticSource diagnosticSource,
+            ActionContext actionContext,
+            bool isPartial,
+            PartialViewResult viewResult,
+            string viewName,
+            IView view)
+        {
+            if (diagnosticSource.IsEnabled("Microsoft.AspNet.Mvc.ViewFound"))
+            {
+                diagnosticSource.Write(
+                    "Microsoft.AspNet.Mvc.ViewFound",
+                    new
+                    {
+                        actionContext = actionContext,
+                        isPartial = isPartial,
+                        result = viewResult,
+                        viewName = viewName,
+                        view = view,
+                    });
+            }
+        }
+
+        public static void ViewNotFound(
+            this DiagnosticSource diagnosticSource,
+            ActionContext actionContext,
+            bool isPartial,
+            PartialViewResult viewResult,
+            string viewName,
+            IEnumerable<string> searchedLocations)
+        {
+            if (diagnosticSource.IsEnabled("Microsoft.AspNet.Mvc.ViewNotFound"))
+            {
+                diagnosticSource.Write(
+                    "Microsoft.AspNet.Mvc.ViewNotFound",
+                    new
+                    {
+                        actionContext = actionContext,
+                        isPartial = isPartial,
+                        result = viewResult,
+                        viewName = viewName,
+                        searchedLocations = searchedLocations,
+                    });
+            }
+        }
+    }
+}

src/Microsoft.AspNet.Mvc.ViewFeatures/ViewComponents/DefaultViewComponentInvoker.cs

@@ -2,10 +2,12 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Diagnostics;
 using System.Reflection;
 using System.Runtime.ExceptionServices;
 using System.Threading.Tasks;
 using Microsoft.AspNet.Mvc.Controllers;
+using Microsoft.AspNet.Mvc.Diagnostics;
 using Microsoft.AspNet.Mvc.Infrastructure;
 using Microsoft.AspNet.Mvc.Rendering;
 using Microsoft.AspNet.Mvc.ViewFeatures;
@@ -16,10 +18,12 @@ namespace Microsoft.AspNet.Mvc.ViewComponents
     {
         private readonly ITypeActivatorCache _typeActivatorCache;
         private readonly IViewComponentActivator _viewComponentActivator;
+        private readonly DiagnosticSource _diagnosticSource;
 
         public DefaultViewComponentInvoker(
             ITypeActivatorCache typeActivatorCache,
-            IViewComponentActivator viewComponentActivator)
+            IViewComponentActivator viewComponentActivator,
+            DiagnosticSource diagnosticSource)
         {
             if (typeActivatorCache == null)
             {
@@ -31,8 +35,14 @@ namespace Microsoft.AspNet.Mvc.ViewComponents
                 throw new ArgumentNullException(nameof(viewComponentActivator));
             }
 
+            if (diagnosticSource == null)
+            {
+                throw new ArgumentNullException(nameof(diagnosticSource));
+            }
+
             _typeActivatorCache = typeActivatorCache;
             _viewComponentActivator = viewComponentActivator;
+            _diagnosticSource = diagnosticSource;
         }
 
         public void Invoke(ViewComponentContext context)
@@ -52,6 +62,7 @@ namespace Microsoft.AspNet.Mvc.ViewComponents
             }
 
             var result = InvokeSyncCore(method, context);
+
             result.Execute(context);
         }
 
@@ -124,9 +135,15 @@ namespace Microsoft.AspNet.Mvc.ViewComponents
 
             var component = CreateComponent(context);
 
+            _diagnosticSource.BeforeViewComponent(context, component);
+
             var result = await ControllerActionExecutor.ExecuteAsync(method, component, context.Arguments);
 
-            return CoerceToViewComponentResult(result);
+            var viewComponentResult = CoerceToViewComponentResult(result);
+
+            _diagnosticSource.AfterViewComponent(context, viewComponentResult, component);
+
+            return viewComponentResult;
         }
 
         public IViewComponentResult InvokeSyncCore(MethodInfo method, ViewComponentContext context)
@@ -145,6 +162,8 @@ namespace Microsoft.AspNet.Mvc.ViewComponents
 
             object result = null;
 
+            _diagnosticSource.BeforeViewComponent(context, component);
+
             try
             {
                 result = method.Invoke(component, context.Arguments);
@@ -156,7 +175,11 @@ namespace Microsoft.AspNet.Mvc.ViewComponents
                 exceptionInfo.Throw();
             }
 
-            return CoerceToViewComponentResult(result);
+            var viewComponentResult = CoerceToViewComponentResult(result);
+
+            _diagnosticSource.AfterViewComponent(context, viewComponentResult, component);
+
+            return viewComponentResult;
         }
 
         private static IViewComponentResult CoerceToViewComponentResult(object value)

src/Microsoft.AspNet.Mvc.ViewFeatures/ViewComponents/DefaultViewComponentInvokerFactory.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Diagnostics;
 using Microsoft.AspNet.Mvc.Infrastructure;
 
 namespace Microsoft.AspNet.Mvc.ViewComponents
@@ -10,13 +11,16 @@ namespace Microsoft.AspNet.Mvc.ViewComponents
     {
         private readonly ITypeActivatorCache _typeActivatorCache;
         private readonly IViewComponentActivator _viewComponentActivator;
+        private readonly DiagnosticSource _diagnosticSource;
 
         public DefaultViewComponentInvokerFactory(
             ITypeActivatorCache typeActivatorCache,
-            IViewComponentActivator viewComponentActivator)
+            IViewComponentActivator viewComponentActivator,
+            DiagnosticSource diagnosticSource)
         {
             _typeActivatorCache = typeActivatorCache;
             _viewComponentActivator = viewComponentActivator;
+            _diagnosticSource = diagnosticSource;
         }
 
         /// <inheritdoc />
@@ -32,7 +36,8 @@ namespace Microsoft.AspNet.Mvc.ViewComponents
 
             return new DefaultViewComponentInvoker(
                 _typeActivatorCache,
-                _viewComponentActivator);
+                _viewComponentActivator,
+                _diagnosticSource);
         }
     }
 }

src/Microsoft.AspNet.Mvc.ViewFeatures/ViewComponents/ViewViewComponentResult.cs

@@ -2,8 +2,10 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Diagnostics;
 using System.Globalization;
 using System.Threading.Tasks;
+using Microsoft.AspNet.Mvc.Diagnostics;
 using Microsoft.AspNet.Mvc.Rendering;
 using Microsoft.AspNet.Mvc.ViewEngines;
 using Microsoft.AspNet.Mvc.ViewFeatures;
@@ -20,6 +22,8 @@ namespace Microsoft.AspNet.Mvc.ViewComponents
         private const string ViewPathFormat = "Components/{0}/{1}";
         private const string DefaultViewName = "Default";
 
+        private DiagnosticSource _diagnosticSource;
+
         /// <summary>
         /// Gets or sets the view name.
         /// </summary>
@@ -115,7 +119,16 @@ namespace Microsoft.AspNet.Mvc.ViewComponents
 
             using (view as IDisposable)
             {
+                if (_diagnosticSource == null)
+                {
+                    _diagnosticSource = context.ViewContext.HttpContext.RequestServices.GetRequiredService<DiagnosticSource>();
+                }
+
+                _diagnosticSource.ViewComponentBeforeViewExecute(context, view);
+
                 await view.RenderAsync(childViewContext);
+
+                _diagnosticSource.ViewComponentAfterViewExecute(context, view);
             }
         }
 

src/Microsoft.AspNet.Mvc.ViewFeatures/ViewFeatures/PartialViewResultExecutor.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Diagnostics;
 using System.Threading.Tasks;
+using Microsoft.AspNet.Mvc.Diagnostics;
 using Microsoft.AspNet.Mvc.Infrastructure;
 using Microsoft.AspNet.Mvc.Logging;
 using Microsoft.AspNet.Mvc.ViewEngines;
@@ -70,37 +71,13 @@ namespace Microsoft.AspNet.Mvc.ViewFeatures
             var result = viewEngine.FindPartialView(actionContext, viewName);
             if (result.Success)
             {
-                if (DiagnosticSource.IsEnabled("Microsoft.AspNet.Mvc.ViewFound"))
+                DiagnosticSource.ViewFound(actionContext, true, viewResult, viewName, result.View);
-                {
-                    DiagnosticSource.Write(
-                        "Microsoft.AspNet.Mvc.ViewFound",
-                        new
-                        {
-                            actionContext = actionContext,
-                            isPartial = true,
-                            result = viewResult,
-                            viewName = viewName,
-                            view = result.View,
-                        });
-                }
 
                 Logger.LogVerbose("The partial view '{PartialViewName}' was found.", viewName);
             }
             else
             {
-                if (DiagnosticSource.IsEnabled("Microsoft.AspNet.Mvc.ViewNotFound"))
+                DiagnosticSource.ViewNotFound(actionContext, true, viewResult, viewName, result.SearchedLocations);
-                {
-                    DiagnosticSource.Write(
-                        "Microsoft.AspNet.Mvc.ViewNotFound",
-                        new
-                        {
-                            actionContext = actionContext,
-                            isPartial = true,
-                            result = viewResult,
-                            viewName = viewName,
-                            searchedLocations = result.SearchedLocations
-                        });
-                }
 
                 Logger.LogError(
                     "The partial view '{PartialViewName}' was not found. Searched locations: {SearchedViewLocations}",

src/Microsoft.AspNet.Mvc.ViewFeatures/ViewFeatures/ViewExecutor.cs

@@ -5,6 +5,7 @@ using System;
 using System.Diagnostics;
 using System.Text;
 using System.Threading.Tasks;
+using Microsoft.AspNet.Mvc.Diagnostics;
 using Microsoft.AspNet.Mvc.Infrastructure;
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.Rendering;
@@ -162,21 +163,11 @@ namespace Microsoft.AspNet.Mvc.ViewFeatures
                     writer,
                     ViewOptions.HtmlHelperOptions);
                 
-                if (DiagnosticSource.IsEnabled("Microsoft.AspNet.Mvc.BeforeView"))
+                DiagnosticSource.BeforeView(view, viewContext);
-                {
-                    DiagnosticSource.Write(
-                        "Microsoft.AspNet.Mvc.BeforeView",
-                        new { view = view, viewContext = viewContext, });
-                }
 
                 await view.RenderAsync(viewContext);
-                
+
-                if (DiagnosticSource.IsEnabled("Microsoft.AspNet.Mvc.AfterView"))
+                DiagnosticSource.AfterView(view, viewContext);
-                {
-                    DiagnosticSource.Write(
-                        "Microsoft.AspNet.Mvc.AfterView",
-                        new { view = view, viewContext = viewContext, });
-                }
 
                 // Perf: Invoke FlushAsync to ensure any buffered content is asynchronously written to the underlying
                 // response asynchronously. In the absence of this line, the buffer gets synchronously written to the

test/Microsoft.AspNet.Mvc.TestDiagnosticListener.Sources/IProxyViewComponentContext.cs

@@ -0,0 +1,9 @@
+// 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.
+
+namespace Microsoft.AspNet.Mvc
+{
+    public interface IProxyViewComponentContext
+    {
+    }
+}

test/Microsoft.AspNet.Mvc.TestDiagnosticListener.Sources/IProxyViewComponentResult.cs

@@ -0,0 +1,9 @@
+// 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.
+
+namespace Microsoft.AspNet.Mvc
+{
+    public interface IProxyViewComponentResult
+    {
+    }
+}

test/Microsoft.AspNet.Mvc.TestDiagnosticListener.Sources/TestDiagnosticListener.cs

@@ -220,5 +220,109 @@ namespace Microsoft.AspNet.Mvc
                 ViewContext = viewContext,
             };
         }
+
+        public class OnBeforeViewComponentEventData
+        {
+            public IProxyActionDescriptor ActionDescriptor { get; set; }
+
+            public IProxyViewComponentContext ViewComponentContext { get; set; }
+
+            public object ViewComponent { get; set; }
+        }
+
+        public OnBeforeViewComponentEventData BeforeViewComponent { get; set; }
+
+        [DiagnosticName("Microsoft.AspNet.Mvc.BeforeViewComponent")]
+        public virtual void OnBeforeViewComponent(
+            IProxyActionDescriptor actionDescriptor,
+            IProxyViewComponentContext viewComponentContext,
+            object viewComponent)
+        {
+            BeforeViewComponent = new OnBeforeViewComponentEventData()
+            {
+                ActionDescriptor = actionDescriptor,
+                ViewComponentContext = viewComponentContext,
+                ViewComponent = viewComponent
+            };
+        }
+
+        public class OnAfterViewComponentEventData
+        {
+            public IProxyActionDescriptor ActionDescriptor { get; set; }
+
+            public IProxyViewComponentContext ViewComponentContext { get; set; }
+
+            public IProxyViewComponentResult ViewComponentResult { get; set; }
+
+            public object ViewComponent { get; set; }
+        }
+
+        public OnAfterViewComponentEventData AfterViewComponent { get; set; }
+
+        [DiagnosticName("Microsoft.AspNet.Mvc.AfterViewComponent")]
+        public virtual void OnAfterViewComponent(
+            IProxyActionDescriptor actionDescriptor,
+            IProxyViewComponentContext viewComponentContext,
+            IProxyViewComponentResult viewComponentResult,
+            object viewComponent)
+        {
+            AfterViewComponent = new OnAfterViewComponentEventData()
+            {
+                ActionDescriptor = actionDescriptor,
+                ViewComponentContext = viewComponentContext,
+                ViewComponentResult = viewComponentResult,
+                ViewComponent = viewComponent
+            };
+        }
+
+        public class OnViewComponentBeforeViewExecuteEventData
+        {
+            public IProxyActionDescriptor ActionDescriptor { get; set; }
+
+            public IProxyViewComponentContext ViewComponentContext { get; set; }
+
+            public IProxyView View { get; set; }
+        }
+
+        public OnViewComponentBeforeViewExecuteEventData ViewComponentBeforeViewExecute { get; set; }
+
+        [DiagnosticName("Microsoft.AspNet.Mvc.ViewComponentBeforeViewExecute")]
+        public virtual void OnViewComponentBeforeViewExecute(
+            IProxyActionDescriptor actionDescriptor,
+            IProxyViewComponentContext viewComponentContext,
+            IProxyView view)
+        {
+            ViewComponentBeforeViewExecute = new OnViewComponentBeforeViewExecuteEventData()
+            {
+                ActionDescriptor = actionDescriptor,
+                ViewComponentContext = viewComponentContext,
+                View = view
+            };
+        }
+
+        public class OnViewComponentAfterViewExecuteEventData
+        {
+            public IProxyActionDescriptor ActionDescriptor { get; set; }
+
+            public IProxyViewComponentContext ViewComponentContext { get; set; }
+
+            public IProxyView View { get; set; }
+        }
+
+        public OnViewComponentAfterViewExecuteEventData ViewComponentAfterViewExecute { get; set; }
+
+        [DiagnosticName("Microsoft.AspNet.Mvc.ViewComponentAfterViewExecute")]
+        public virtual void OnViewComponentAfterViewExecute(
+            IProxyActionDescriptor actionDescriptor,
+            IProxyViewComponentContext viewComponentContext,
+            IProxyView view)
+        {
+            ViewComponentAfterViewExecute = new OnViewComponentAfterViewExecuteEventData()
+            {
+                ActionDescriptor = actionDescriptor,
+                ViewComponentContext = viewComponentContext,
+                View = view
+            };
+        }
     }
 }

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/ViewComponentResultTest.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Text;
 using System.Threading.Tasks;
@@ -103,7 +104,7 @@ namespace Microsoft.AspNet.Mvc
             var expected = $"A view component named '{typeof(TextViewComponent).FullName}' could not be found.";
 
             var actionContext = CreateActionContext();
-            var services = CreateServices(actionContext.HttpContext);
+            var services = CreateServices(diagnosticListener: null, context: actionContext.HttpContext);
             services.AddSingleton<IViewComponentSelector>();
 
 
@@ -175,6 +176,44 @@ namespace Microsoft.AspNet.Mvc
             Assert.Equal("Hello-Async, World!", body);
         }
 
+        [Fact]
+        public async Task ExecuteResultAsync_ExecutesViewComponent_AndWritesDiagnosticSource()
+        {
+            // Arrange
+            var descriptor = new ViewComponentDescriptor()
+            {
+                FullName = "Full.Name.Text",
+                ShortName = "Text",
+                Type = typeof(TextViewComponent),
+            };
+
+            var adapter = new TestDiagnosticListener();
+
+            var actionContext = CreateActionContext(adapter, descriptor);
+
+            var viewComponentResult = new ViewComponentResult()
+            {
+                Arguments = new object[] { "World!" },
+                ViewComponentName = "Text",
+                TempData = _tempDataDictionary,
+            };
+
+            // Act
+            await viewComponentResult.ExecuteResultAsync(actionContext);
+
+            // Assert
+            var body = ReadBody(actionContext.HttpContext.Response);
+            Assert.Equal("Hello, World!", body);
+
+            Assert.NotNull(adapter.BeforeViewComponent?.ActionDescriptor);
+            Assert.NotNull(adapter.BeforeViewComponent?.ViewComponentContext);
+            Assert.NotNull(adapter.BeforeViewComponent?.ViewComponent);
+            Assert.NotNull(adapter.AfterViewComponent?.ActionDescriptor);
+            Assert.NotNull(adapter.AfterViewComponent?.ViewComponentContext);
+            Assert.NotNull(adapter.AfterViewComponent?.ViewComponentResult);
+            Assert.NotNull(adapter.AfterViewComponent?.ViewComponent);
+        }
+
         [Fact]
         public async Task ExecuteResultAsync_ExecutesViewComponent_ByShortName()
         {
@@ -413,12 +452,18 @@ namespace Microsoft.AspNet.Mvc
             Assert.Equal(expectedContentType, actionContext.HttpContext.Response.ContentType);
         }
 
-        private IServiceCollection CreateServices(HttpContext context, params ViewComponentDescriptor[] descriptors)
+        private IServiceCollection CreateServices(object diagnosticListener, HttpContext context, params ViewComponentDescriptor[] descriptors)
         { 
             var httpContext = new HttpContextAccessor() { HttpContext = context };
             var tempDataProvider = new SessionStateTempDataProvider();
+            var diagnosticSource = new DiagnosticListener("Microsoft.AspNet");
+            if (diagnosticListener != null)
+            {
+                diagnosticSource.SubscribeWithAdapter(diagnosticListener);
+            }
 
             var services = new ServiceCollection();
+            services.AddInstance<DiagnosticSource>(diagnosticSource);
             services.AddSingleton<IOptions<MvcViewOptions>, TestOptionsManager<MvcViewOptions>>();
             services.AddTransient<IViewComponentHelper, DefaultViewComponentHelper>();
             services.AddSingleton<IViewComponentSelector, DefaultViewComponentSelector>();
@@ -435,10 +480,10 @@ namespace Microsoft.AspNet.Mvc
             return services;
         }
 
-        private HttpContext CreateHttpContext(params ViewComponentDescriptor[] descriptors)
+        private HttpContext CreateHttpContext(object diagnosticListener, params ViewComponentDescriptor[] descriptors)
         {
             var httpContext = new DefaultHttpContext();
-            var services = CreateServices(httpContext, descriptors);
+            var services = CreateServices(diagnosticListener, httpContext, descriptors);
 
             httpContext.Response.Body = new MemoryStream();
             httpContext.RequestServices = services.BuildServiceProvider();
@@ -446,11 +491,17 @@ namespace Microsoft.AspNet.Mvc
             return httpContext;
         }
 
+        private ActionContext CreateActionContext(object diagnosticListener, params ViewComponentDescriptor[] descriptors)
+        {
+            return new ActionContext(CreateHttpContext(diagnosticListener, descriptors), new RouteData(), new ActionDescriptor());
+        }
+
         private ActionContext CreateActionContext(params ViewComponentDescriptor[] descriptors)
         {
-            return new ActionContext(CreateHttpContext(descriptors), new RouteData(), new ActionDescriptor());
+            return CreateActionContext(null, descriptors);
         }
 
+
         private class FixedSetViewComponentDescriptorProvider : IViewComponentDescriptorProvider
         {
             private readonly ViewComponentDescriptor[] _descriptors;

test/Microsoft.AspNet.Mvc.ViewFeatures.Test/ViewComponents/ViewViewComponentResultTest.cs

@@ -3,6 +3,7 @@
 
 #if MOCK_SUPPORT
 using System;
+using System.Diagnostics;
 using System.IO;
 using System.Threading.Tasks;
 using Microsoft.AspNet.Http.Internal;
@@ -91,6 +92,48 @@ namespace Microsoft.AspNet.Mvc
             view.Verify();
         }
 
+        [Fact]
+        public void Execute_ResolvesView_AndWritesDiagnosticSource()
+        {
+            // Arrange
+            var view = new Mock<IView>(MockBehavior.Strict);
+            view.Setup(v => v.RenderAsync(It.IsAny<ViewContext>()))
+                .Returns(Task.FromResult(result: true))
+                .Verifiable();
+
+            var viewEngine = new Mock<IViewEngine>(MockBehavior.Strict);
+            viewEngine.Setup(e => e.FindPartialView(It.IsAny<ActionContext>(), It.IsAny<string>()))
+                      .Returns(ViewEngineResult.Found("Default", view.Object))
+                      .Verifiable();
+
+            var viewData = new ViewDataDictionary(new EmptyModelMetadataProvider());
+
+            var result = new ViewViewComponentResult
+            {
+                ViewEngine = viewEngine.Object,
+                ViewData = viewData,
+                TempData = _tempDataDictionary,
+            };
+
+            var adapter = new TestDiagnosticListener();
+
+            var viewComponentContext = GetViewComponentContext(view.Object, viewData, adapter);
+
+            // Act
+            result.Execute(viewComponentContext);
+
+            // Assert
+            viewEngine.Verify();
+            view.Verify();
+
+            Assert.NotNull(adapter.ViewComponentBeforeViewExecute?.ActionDescriptor);
+            Assert.NotNull(adapter.ViewComponentBeforeViewExecute?.ViewComponentContext);
+            Assert.NotNull(adapter.ViewComponentBeforeViewExecute?.View);
+            Assert.NotNull(adapter.ViewComponentAfterViewExecute?.ActionDescriptor);
+            Assert.NotNull(adapter.ViewComponentAfterViewExecute?.ViewComponentContext);
+            Assert.NotNull(adapter.ViewComponentAfterViewExecute?.View);
+        }
+
         [Fact]
         public void Execute_ThrowsIfPartialViewCannotBeFound()
         {
@@ -204,6 +247,8 @@ namespace Microsoft.AspNet.Mvc
             var serviceProvider = new Mock<IServiceProvider>();
             serviceProvider.Setup(p => p.GetService(typeof(ICompositeViewEngine)))
                 .Returns(viewEngine.Object);
+            serviceProvider.Setup(p => p.GetService(typeof(DiagnosticSource)))
+                .Returns(new DiagnosticListener("Test"));
 
             var viewData = new ViewDataDictionary(new EmptyModelMetadataProvider());
 
@@ -345,9 +390,23 @@ namespace Microsoft.AspNet.Mvc
             viewEngine.Verify();
         }
 
-        private static ViewComponentContext GetViewComponentContext(IView view, ViewDataDictionary viewData)
+        private static ViewComponentContext GetViewComponentContext(IView view, ViewDataDictionary viewData, object diagnosticListener = null)
         {
-            var actionContext = new ActionContext(new DefaultHttpContext(), new RouteData(), new ActionDescriptor());
+            var diagnosticSource = new DiagnosticListener("Microsoft.AspNet");
+            if (diagnosticListener == null)
+            {
+                diagnosticListener = new TestDiagnosticListener();
+            }
+
+            diagnosticSource.SubscribeWithAdapter(diagnosticListener);
+
+            var serviceProvider = new Mock<IServiceProvider>();
+            serviceProvider.Setup(s => s.GetService(typeof(DiagnosticSource))).Returns(diagnosticSource);
+
+            var httpContext = new DefaultHttpContext();
+            httpContext.RequestServices = serviceProvider.Object;
+
+            var actionContext = new ActionContext(httpContext, new RouteData(), new ActionDescriptor());
             var viewContext = new ViewContext(
                 actionContext,
                 view,