From 1c2e94568552c31d26333180c15392409ee4404e Mon Sep 17 00:00:00 2001
From: Pranav K <prkrishn@hotmail.com>
Date: Tue, 18 Jan 2022 12:57:53 -0800
Subject: [PATCH] Use view buffers during pre-rendering (#39465)

* Use view buffers during rendering

This change removes about 8kb of string[] allocations per request during pre-rendering and replaces them with a ViewBuffer that uses array pooling. The allocations come from list resizing as part of HtmlRenderer operations (such as https://github.com/dotnet/aspnetcore/blob/main/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/HtmlRenderer.cs#L133-L134). Also includes a couple of other clean up items:

* Uses ValueTask instead of `Task<T>`
* Moves top-level types to a separate file.
* Some formatting cleanup
---
 ....AspNetCore.Components.Server.Tests.csproj |  3 +-
 .../test/ComponentTagHelperTest.cs            |  2 +-
 .../PersistComponentStateTagHelperTest.cs     |  4 +-
 .../Infrastructure/ComponentHtmlContent.cs    | 29 -------
 .../RazorComponents/ComponentRenderedText.cs  |  8 +-
 .../src/RazorComponents/ComponentRenderer.cs  | 68 +++++++---------
 .../src/RazorComponents/HtmlRenderer.cs       | 77 ++++++++++---------
 .../src/RazorComponents/IComponentRenderer.cs |  4 +-
 .../src/RazorComponents/InvokedRenderModes.cs | 31 ++++++++
 .../StaticComponentRenderer.cs                |  7 +-
 .../HtmlHelperComponentExtensions.cs          |  6 +-
 .../src/ServerComponentSerializer.cs          | 48 ++++--------
 .../src/WebAssemblyComponentSerializer.cs     | 43 +++--------
 .../RazorComponents/ComponentRendererTest.cs  | 43 ++++++-----
 .../test/RazorComponents/HtmlRendererTest.cs  | 66 ++++++++++------
 .../HtmlHelperComponentExtensionsTest.cs      |  4 +-
 16 files changed, 210 insertions(+), 233 deletions(-)
 delete mode 100644 src/Mvc/Mvc.ViewFeatures/src/Infrastructure/ComponentHtmlContent.cs
 create mode 100644 src/Mvc/Mvc.ViewFeatures/src/RazorComponents/InvokedRenderModes.cs

diff --git a/src/Components/Server/test/Microsoft.AspNetCore.Components.Server.Tests.csproj b/src/Components/Server/test/Microsoft.AspNetCore.Components.Server.Tests.csproj
index 2463622ac4a3..69c2897fdb6d 100644
--- a/src/Components/Server/test/Microsoft.AspNetCore.Components.Server.Tests.csproj
+++ b/src/Components/Server/test/Microsoft.AspNetCore.Components.Server.Tests.csproj
@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <TargetFramework>$(DefaultNetCoreTargetFramework)</TargetFramework>
@@ -6,6 +6,7 @@
 
   <ItemGroup>
     <Reference Include="Microsoft.AspNetCore.Components.Server" />
+    <Reference Include="Microsoft.AspNetCore.Html.Abstractions" />
   </ItemGroup>
 
   <PropertyGroup>
diff --git a/src/Mvc/Mvc.TagHelpers/test/ComponentTagHelperTest.cs b/src/Mvc/Mvc.TagHelpers/test/ComponentTagHelperTest.cs
index 41d5c4456703..d4778092498e 100644
--- a/src/Mvc/Mvc.TagHelpers/test/ComponentTagHelperTest.cs
+++ b/src/Mvc/Mvc.TagHelpers/test/ComponentTagHelperTest.cs
@@ -75,7 +75,7 @@ private ViewContext GetViewContext()
     {
         var htmlContent = new HtmlContentBuilder().AppendHtml("Hello world");
         var renderer = Mock.Of<IComponentRenderer>(c =>
-            c.RenderComponentAsync(It.IsAny<ViewContext>(), It.IsAny<Type>(), It.IsAny<RenderMode>(), It.IsAny<object>()) == Task.FromResult<IHtmlContent>(htmlContent));
+            c.RenderComponentAsync(It.IsAny<ViewContext>(), It.IsAny<Type>(), It.IsAny<RenderMode>(), It.IsAny<object>()) == new ValueTask<IHtmlContent>(htmlContent));
 
         var httpContext = new DefaultHttpContext
         {
diff --git a/src/Mvc/Mvc.TagHelpers/test/PersistComponentStateTagHelperTest.cs b/src/Mvc/Mvc.TagHelpers/test/PersistComponentStateTagHelperTest.cs
index 81b309cdd13f..2df13c0ceb10 100644
--- a/src/Mvc/Mvc.TagHelpers/test/PersistComponentStateTagHelperTest.cs
+++ b/src/Mvc/Mvc.TagHelpers/test/PersistComponentStateTagHelperTest.cs
@@ -9,6 +9,7 @@
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.Rendering;
 using Microsoft.AspNetCore.Mvc.ViewFeatures;
+using Microsoft.AspNetCore.Mvc.ViewFeatures.Buffers;
 using Microsoft.AspNetCore.Razor.TagHelpers;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
@@ -180,7 +181,7 @@ private ViewContext GetViewContext()
     {
         var htmlContent = new HtmlContentBuilder().AppendHtml("Hello world");
         var renderer = Mock.Of<IComponentRenderer>(c =>
-            c.RenderComponentAsync(It.IsAny<ViewContext>(), It.IsAny<Type>(), It.IsAny<RenderMode>(), It.IsAny<object>()) == Task.FromResult<IHtmlContent>(htmlContent));
+            c.RenderComponentAsync(It.IsAny<ViewContext>(), It.IsAny<Type>(), It.IsAny<RenderMode>(), It.IsAny<object>()) == new ValueTask<IHtmlContent>(htmlContent));
 
         var httpContext = new DefaultHttpContext
         {
@@ -191,6 +192,7 @@ private ViewContext GetViewContext()
                 .AddSingleton(_ephemeralProvider)
                 .AddSingleton<ILoggerFactory>(NullLoggerFactory.Instance)
                 .AddSingleton(HtmlEncoder.Default)
+                .AddScoped<IViewBufferScope, TestViewBufferScope>()
                 .BuildServiceProvider(),
         };
 
diff --git a/src/Mvc/Mvc.ViewFeatures/src/Infrastructure/ComponentHtmlContent.cs b/src/Mvc/Mvc.ViewFeatures/src/Infrastructure/ComponentHtmlContent.cs
deleted file mode 100644
index be2eca6bb73b..000000000000
--- a/src/Mvc/Mvc.ViewFeatures/src/Infrastructure/ComponentHtmlContent.cs
+++ /dev/null
@@ -1,29 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-
-using System.Linq;
-using System.Text.Encodings.Web;
-using Microsoft.AspNetCore.Html;
-
-namespace Microsoft.AspNetCore.Mvc.ViewFeatures;
-
-internal class ComponentHtmlContent : IHtmlContent
-{
-    private readonly IEnumerable<string> _preamble;
-    private readonly IEnumerable<string> _componentResult;
-    private readonly IEnumerable<string> _epilogue;
-
-    public ComponentHtmlContent(IEnumerable<string> componentResult)
-        : this(Array.Empty<string>(), componentResult, Array.Empty<string>()) { }
-
-    public ComponentHtmlContent(IEnumerable<string> preamble, IEnumerable<string> componentResult, IEnumerable<string> epilogue) =>
-        (_preamble, _componentResult, _epilogue) = (preamble, componentResult, epilogue);
-
-    public void WriteTo(TextWriter writer, HtmlEncoder encoder)
-    {
-        foreach (var element in _preamble.Concat(_componentResult).Concat(_epilogue))
-        {
-            writer.Write(element);
-        }
-    }
-}
diff --git a/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/ComponentRenderedText.cs b/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/ComponentRenderedText.cs
index 806a58c3ed6c..2f3f3cf7fe71 100644
--- a/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/ComponentRenderedText.cs
+++ b/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/ComponentRenderedText.cs
@@ -1,17 +1,19 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using Microsoft.AspNetCore.Html;
+
 namespace Microsoft.AspNetCore.Components.Rendering;
 
 internal readonly struct ComponentRenderedText
 {
-    public ComponentRenderedText(int componentId, IEnumerable<string> tokens)
+    public ComponentRenderedText(int componentId, IHtmlContent htmlContent)
     {
         ComponentId = componentId;
-        Tokens = tokens;
+        HtmlContent = htmlContent;
     }
 
     public int ComponentId { get; }
 
-    public IEnumerable<string> Tokens { get; }
+    public IHtmlContent HtmlContent { get; }
 }
diff --git a/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/ComponentRenderer.cs b/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/ComponentRenderer.cs
index 6f143397464f..8ff7c8af3c9f 100644
--- a/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/ComponentRenderer.cs
+++ b/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/ComponentRenderer.cs
@@ -5,29 +5,30 @@
 using Microsoft.AspNetCore.Html;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.Rendering;
+using Microsoft.AspNetCore.Mvc.ViewFeatures.Buffers;
 
 namespace Microsoft.AspNetCore.Mvc.ViewFeatures;
 
-internal class ComponentRenderer : IComponentRenderer
+internal sealed class ComponentRenderer : IComponentRenderer
 {
     private static readonly object ComponentSequenceKey = new object();
     private static readonly object InvokedRenderModesKey = new object();
 
     private readonly StaticComponentRenderer _staticComponentRenderer;
     private readonly ServerComponentSerializer _serverComponentSerializer;
-    private readonly WebAssemblyComponentSerializer _WebAssemblyComponentSerializer;
+    private readonly IViewBufferScope _viewBufferScope;
 
     public ComponentRenderer(
         StaticComponentRenderer staticComponentRenderer,
         ServerComponentSerializer serverComponentSerializer,
-        WebAssemblyComponentSerializer WebAssemblyComponentSerializer)
+        IViewBufferScope viewBufferScope)
     {
         _staticComponentRenderer = staticComponentRenderer;
         _serverComponentSerializer = serverComponentSerializer;
-        _WebAssemblyComponentSerializer = WebAssemblyComponentSerializer;
+        _viewBufferScope = viewBufferScope;
     }
 
-    public async Task<IHtmlContent> RenderComponentAsync(
+    public async ValueTask<IHtmlContent> RenderComponentAsync(
         ViewContext viewContext,
         Type componentType,
         RenderMode renderMode,
@@ -117,14 +118,12 @@ internal static InvokedRenderModes.Mode GetPersistStateRenderMode(ViewContext vi
         }
     }
 
-    private async Task<IHtmlContent> StaticComponentAsync(HttpContext context, Type type, ParameterView parametersCollection)
+    private ValueTask<IHtmlContent> StaticComponentAsync(HttpContext context, Type type, ParameterView parametersCollection)
     {
-        var result = await _staticComponentRenderer.PrerenderComponentAsync(
+        return _staticComponentRenderer.PrerenderComponentAsync(
             parametersCollection,
             context,
             type);
-
-        return new ComponentHtmlContent(result);
     }
 
     private async Task<IHtmlContent> PrerenderedServerComponentAsync(HttpContext context, ServerComponentInvocationSequence invocationId, Type type, ParameterView parametersCollection)
@@ -145,13 +144,15 @@ private async Task<IHtmlContent> PrerenderedServerComponentAsync(HttpContext con
             context,
             type);
 
-        return new ComponentHtmlContent(
-            ServerComponentSerializer.GetPreamble(currentInvocation),
-            result,
-            ServerComponentSerializer.GetEpilogue(currentInvocation));
+        var viewBuffer = new ViewBuffer(_viewBufferScope, nameof(ComponentRenderer), ViewBuffer.ViewPageSize);
+        ServerComponentSerializer.AppendPreamble(viewBuffer, currentInvocation);
+        viewBuffer.AppendHtml(result);
+        ServerComponentSerializer.AppendEpilogue(viewBuffer, currentInvocation);
+
+        return viewBuffer;
     }
 
-    private async Task<IHtmlContent> PrerenderedWebAssemblyComponentAsync(HttpContext context, Type type, ParameterView parametersCollection)
+    private async ValueTask<IHtmlContent> PrerenderedWebAssemblyComponentAsync(HttpContext context, Type type, ParameterView parametersCollection)
     {
         var currentInvocation = WebAssemblyComponentSerializer.SerializeInvocation(
             type,
@@ -163,10 +164,12 @@ private async Task<IHtmlContent> PrerenderedWebAssemblyComponentAsync(HttpContex
             context,
             type);
 
-        return new ComponentHtmlContent(
-            WebAssemblyComponentSerializer.GetPreamble(currentInvocation),
-            result,
-            WebAssemblyComponentSerializer.GetEpilogue(currentInvocation));
+        var viewBuffer = new ViewBuffer(_viewBufferScope, nameof(ComponentRenderer), ViewBuffer.ViewPageSize);
+        WebAssemblyComponentSerializer.AppendPreamble(viewBuffer, currentInvocation);
+        viewBuffer.AppendHtml(result);
+        WebAssemblyComponentSerializer.AppendEpilogue(viewBuffer, currentInvocation);
+
+        return viewBuffer;
     }
 
     private IHtmlContent NonPrerenderedServerComponent(HttpContext context, ServerComponentInvocationSequence invocationId, Type type, ParameterView parametersCollection)
@@ -178,31 +181,16 @@ private IHtmlContent NonPrerenderedServerComponent(HttpContext context, ServerCo
 
         var currentInvocation = _serverComponentSerializer.SerializeInvocation(invocationId, type, parametersCollection, prerendered: false);
 
-        return new ComponentHtmlContent(ServerComponentSerializer.GetPreamble(currentInvocation));
+        var viewBuffer = new ViewBuffer(_viewBufferScope, nameof(ComponentRenderer), ServerComponentSerializer.PreambleBufferSize);
+        ServerComponentSerializer.AppendPreamble(viewBuffer, currentInvocation);
+        return viewBuffer;
     }
 
-    private static IHtmlContent NonPrerenderedWebAssemblyComponent(HttpContext context, Type type, ParameterView parametersCollection)
+    private IHtmlContent NonPrerenderedWebAssemblyComponent(HttpContext context, Type type, ParameterView parametersCollection)
     {
         var currentInvocation = WebAssemblyComponentSerializer.SerializeInvocation(type, parametersCollection, prerendered: false);
-
-        return new ComponentHtmlContent(WebAssemblyComponentSerializer.GetPreamble(currentInvocation));
-    }
-}
-
-internal class InvokedRenderModes
-{
-    public InvokedRenderModes(Mode mode)
-    {
-        Value = mode;
-    }
-
-    public Mode Value { get; set; }
-
-    internal enum Mode
-    {
-        None,
-        Server,
-        WebAssembly,
-        ServerAndWebAssembly
+        var viewBuffer = new ViewBuffer(_viewBufferScope, nameof(ComponentRenderer), ServerComponentSerializer.PreambleBufferSize);
+        WebAssemblyComponentSerializer.AppendPreamble(viewBuffer, currentInvocation);
+        return viewBuffer;
     }
 }
diff --git a/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/HtmlRenderer.cs b/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/HtmlRenderer.cs
index f629976b7f02..2fa943a3497a 100644
--- a/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/HtmlRenderer.cs
+++ b/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/HtmlRenderer.cs
@@ -3,27 +3,26 @@
 
 using System.Diagnostics;
 using System.Runtime.ExceptionServices;
-using System.Text.Encodings.Web;
 using Microsoft.AspNetCore.Components.RenderTree;
+using Microsoft.AspNetCore.Mvc.ViewFeatures.Buffers;
 using Microsoft.Extensions.Logging;
 
 namespace Microsoft.AspNetCore.Components.Rendering;
 
-internal class HtmlRenderer : Renderer
+internal sealed class HtmlRenderer : Renderer
 {
     private static readonly HashSet<string> SelfClosingElements = new HashSet<string>(StringComparer.OrdinalIgnoreCase)
-        {
-            "area", "base", "br", "col", "embed", "hr", "img", "input", "link", "meta", "param", "source", "track", "wbr"
-        };
+    {
+        "area", "base", "br", "col", "embed", "hr", "img", "input", "link", "meta", "param", "source", "track", "wbr"
+    };
 
     private static readonly Task CanceledRenderTask = Task.FromCanceled(new CancellationToken(canceled: true));
+    private readonly IViewBufferScope _viewBufferScope;
 
-    private readonly Func<string, string> _htmlEncoder;
-
-    public HtmlRenderer(IServiceProvider serviceProvider, ILoggerFactory loggerFactory, HtmlEncoder htmlEncoder)
+    public HtmlRenderer(IServiceProvider serviceProvider, ILoggerFactory loggerFactory, IViewBufferScope viewBufferScope)
         : base(serviceProvider, loggerFactory)
     {
-        _htmlEncoder = htmlEncoder.Encode;
+        _viewBufferScope = viewBufferScope;
     }
 
     public override Dispatcher Dispatcher { get; } = Dispatcher.CreateDefault();
@@ -50,10 +49,12 @@ public async Task<ComponentRenderedText> RenderComponentAsync(Type componentType
     {
         var (componentId, frames) = await CreateInitialRenderAsync(componentType, initialParameters);
 
-        var context = new HtmlRenderingContext();
+        var viewBuffer = new ViewBuffer(_viewBufferScope, nameof(HtmlRenderer), ViewBuffer.ViewPageSize);
+
+        var context = new HtmlRenderingContext { HtmlContentBuilder = viewBuffer, };
         var newPosition = RenderFrames(context, frames, 0, frames.Count);
         Debug.Assert(newPosition == frames.Count);
-        return new ComponentRenderedText(componentId, context.Result);
+        return new ComponentRenderedText(componentId, context.HtmlContentBuilder);
     }
 
     public Task<ComponentRenderedText> RenderComponentAsync<TComponent>(ParameterView initialParameters) where TComponent : IComponent
@@ -95,10 +96,10 @@ private int RenderCore(
             case RenderTreeFrameType.Attribute:
                 throw new InvalidOperationException($"Attributes should only be encountered within {nameof(RenderElement)}");
             case RenderTreeFrameType.Text:
-                context.Result.Add(_htmlEncoder(frame.TextContent));
+                context.HtmlContentBuilder.Append(frame.TextContent);
                 return ++position;
             case RenderTreeFrameType.Markup:
-                context.Result.Add(frame.MarkupContent);
+                context.HtmlContentBuilder.AppendHtml(frame.MarkupContent);
                 return ++position;
             case RenderTreeFrameType.Component:
                 return RenderChildComponent(context, frames, position);
@@ -129,9 +130,9 @@ private int RenderElement(
         int position)
     {
         ref var frame = ref frames.Array[position];
-        var result = context.Result;
-        result.Add("<");
-        result.Add(frame.ElementName);
+        var result = context.HtmlContentBuilder;
+        result.AppendHtml("<");
+        result.AppendHtml(frame.ElementName);
         var afterAttributes = RenderAttributes(context, frames, position + 1, frame.ElementSubtreeLength - 1, out var capturedValueAttribute);
 
         // When we see an <option> as a descendant of a <select>, and the option's "value" attribute matches the
@@ -141,13 +142,13 @@ private int RenderElement(
             && string.Equals(frame.ElementName, "option", StringComparison.OrdinalIgnoreCase)
             && string.Equals(capturedValueAttribute, context.ClosestSelectValueAsString, StringComparison.Ordinal))
         {
-            result.Add(" selected");
+            result.AppendHtml(" selected");
         }
 
         var remainingElements = frame.ElementSubtreeLength + position - afterAttributes;
         if (remainingElements > 0)
         {
-            result.Add(">");
+            result.AppendHtml(">");
 
             var isSelect = string.Equals(frame.ElementName, "select", StringComparison.OrdinalIgnoreCase);
             if (isSelect)
@@ -164,9 +165,9 @@ private int RenderElement(
                 context.ClosestSelectValueAsString = null;
             }
 
-            result.Add("</");
-            result.Add(frame.ElementName);
-            result.Add(">");
+            result.AppendHtml("</");
+            result.AppendHtml(frame.ElementName);
+            result.AppendHtml(">");
             Debug.Assert(afterElement == position + frame.ElementSubtreeLength);
             return afterElement;
         }
@@ -174,14 +175,14 @@ private int RenderElement(
         {
             if (SelfClosingElements.Contains(frame.ElementName))
             {
-                result.Add(" />");
+                result.AppendHtml(" />");
             }
             else
             {
-                result.Add(">");
-                result.Add("</");
-                result.Add(frame.ElementName);
-                result.Add(">");
+                result.AppendHtml(">");
+                result.AppendHtml("</");
+                result.AppendHtml(frame.ElementName);
+                result.AppendHtml(">");
             }
             Debug.Assert(afterAttributes == position + frame.ElementSubtreeLength);
             return afterAttributes;
@@ -198,7 +199,7 @@ private int RenderChildren(HtmlRenderingContext context, ArrayRange<RenderTreeFr
         return RenderFrames(context, frames, position, maxElements);
     }
 
-    private int RenderAttributes(
+    private static int RenderAttributes(
         HtmlRenderingContext context,
         ArrayRange<RenderTreeFrame> frames, int position, int maxElements, out string capturedValueAttribute)
     {
@@ -209,7 +210,7 @@ private int RenderAttributes(
             return position;
         }
 
-        var result = context.Result;
+        var result = context.HtmlContentBuilder;
 
         for (var i = 0; i < maxElements; i++)
         {
@@ -228,16 +229,16 @@ private int RenderAttributes(
             switch (frame.AttributeValue)
             {
                 case bool flag when flag:
-                    result.Add(" ");
-                    result.Add(frame.AttributeName);
+                    result.AppendHtml(" ");
+                    result.AppendHtml(frame.AttributeName);
                     break;
                 case string value:
-                    result.Add(" ");
-                    result.Add(frame.AttributeName);
-                    result.Add("=");
-                    result.Add("\"");
-                    result.Add(_htmlEncoder(value));
-                    result.Add("\"");
+                    result.AppendHtml(" ");
+                    result.AppendHtml(frame.AttributeName);
+                    result.AppendHtml("=");
+                    result.AppendHtml("\"");
+                    result.Append(value);
+                    result.AppendHtml("\"");
                     break;
                 default:
                     break;
@@ -257,9 +258,9 @@ private int RenderAttributes(
         return (componentId, GetCurrentRenderTreeFrames(componentId));
     }
 
-    private class HtmlRenderingContext
+    private sealed class HtmlRenderingContext
     {
-        public List<string> Result { get; } = new List<string>();
+        public ViewBuffer HtmlContentBuilder { get; init; }
 
         public string ClosestSelectValueAsString { get; set; }
     }
diff --git a/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/IComponentRenderer.cs b/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/IComponentRenderer.cs
index 3ab315e95ef0..2fe99908545e 100644
--- a/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/IComponentRenderer.cs
+++ b/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/IComponentRenderer.cs
@@ -1,4 +1,4 @@
-// Licensed to the .NET Foundation under one or more agreements.
+// Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using Microsoft.AspNetCore.Html;
@@ -8,7 +8,7 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures;
 
 internal interface IComponentRenderer
 {
-    Task<IHtmlContent> RenderComponentAsync(
+    ValueTask<IHtmlContent> RenderComponentAsync(
         ViewContext viewContext,
         Type componentType,
         RenderMode renderMode,
diff --git a/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/InvokedRenderModes.cs b/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/InvokedRenderModes.cs
new file mode 100644
index 000000000000..ad44136bdd63
--- /dev/null
+++ b/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/InvokedRenderModes.cs
@@ -0,0 +1,31 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.AspNetCore.Mvc.Rendering;
+
+namespace Microsoft.AspNetCore.Mvc.ViewFeatures;
+
+internal sealed class InvokedRenderModes
+{
+    public InvokedRenderModes(Mode mode)
+    {
+        Value = mode;
+    }
+
+    public Mode Value { get; set; }
+
+    /// <summary>
+    /// Tracks <see cref="RenderMode"/> for components.
+    /// </summary>
+    internal enum Mode
+    {
+        None,
+        Server,
+        WebAssembly,
+
+        /// <summary>
+        /// Tracks an app that has both components rendered both on the Server and WebAssembly.
+        /// </summary>
+        ServerAndWebAssembly
+    }
+}
diff --git a/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/StaticComponentRenderer.cs b/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/StaticComponentRenderer.cs
index f5171c2c32fb..204af65183f9 100644
--- a/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/StaticComponentRenderer.cs
+++ b/src/Mvc/Mvc.ViewFeatures/src/RazorComponents/StaticComponentRenderer.cs
@@ -6,6 +6,7 @@
 using Microsoft.AspNetCore.Components.Infrastructure;
 using Microsoft.AspNetCore.Components.Rendering;
 using Microsoft.AspNetCore.Components.Routing;
+using Microsoft.AspNetCore.Html;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Extensions;
 using Microsoft.Extensions.DependencyInjection;
@@ -23,7 +24,7 @@ public StaticComponentRenderer(HtmlRenderer renderer)
         _renderer = renderer;
     }
 
-    public async Task<IEnumerable<string>> PrerenderComponentAsync(
+    public async ValueTask<IHtmlContent> PrerenderComponentAsync(
         ParameterView parameters,
         HttpContext httpContext,
         Type componentType)
@@ -51,10 +52,10 @@ public async Task<IEnumerable<string>> PrerenderComponentAsync(
             }
 
             httpContext.Response.Redirect(navigationException.Location);
-            return Array.Empty<string>();
+            return HtmlString.Empty;
         }
 
-        return result.Tokens;
+        return result.HtmlContent;
     }
 
     private Task InitializeStandardComponentServicesAsync(HttpContext httpContext)
diff --git a/src/Mvc/Mvc.ViewFeatures/src/Rendering/HtmlHelperComponentExtensions.cs b/src/Mvc/Mvc.ViewFeatures/src/Rendering/HtmlHelperComponentExtensions.cs
index abb8c62110c1..e960f7c17c0c 100644
--- a/src/Mvc/Mvc.ViewFeatures/src/Rendering/HtmlHelperComponentExtensions.cs
+++ b/src/Mvc/Mvc.ViewFeatures/src/Rendering/HtmlHelperComponentExtensions.cs
@@ -1,4 +1,4 @@
-// Licensed to the .NET Foundation under one or more agreements.
+// Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using Microsoft.AspNetCore.Components;
@@ -44,7 +44,7 @@ public static Task<IHtmlContent> RenderComponentAsync<TComponent>(
     /// <param name="parameters">An <see cref="object"/> containing the parameters to pass
     /// to the component.</param>
     /// <param name="renderMode">The <see cref="RenderMode"/> for the component.</param>
-    public static Task<IHtmlContent> RenderComponentAsync(
+    public static async Task<IHtmlContent> RenderComponentAsync(
         this IHtmlHelper htmlHelper,
         Type componentType,
         RenderMode renderMode,
@@ -62,6 +62,6 @@ public static Task<IHtmlContent> RenderComponentAsync(
 
         var viewContext = htmlHelper.ViewContext;
         var componentRenderer = viewContext.HttpContext.RequestServices.GetRequiredService<IComponentRenderer>();
-        return componentRenderer.RenderComponentAsync(viewContext, componentType, renderMode, parameters);
+        return await componentRenderer.RenderComponentAsync(viewContext, componentType, renderMode, parameters);
     }
 }
diff --git a/src/Mvc/Mvc.ViewFeatures/src/ServerComponentSerializer.cs b/src/Mvc/Mvc.ViewFeatures/src/ServerComponentSerializer.cs
index 2b9d6264ec3c..677264a1b7c7 100644
--- a/src/Mvc/Mvc.ViewFeatures/src/ServerComponentSerializer.cs
+++ b/src/Mvc/Mvc.ViewFeatures/src/ServerComponentSerializer.cs
@@ -4,12 +4,15 @@
 using System.Text.Json;
 using Microsoft.AspNetCore.Components;
 using Microsoft.AspNetCore.DataProtection;
+using Microsoft.AspNetCore.Html;
 
 namespace Microsoft.AspNetCore.Mvc.ViewFeatures;
 
 // See the details of the component serialization protocol in ServerComponentDeserializer.cs on the Components solution.
 internal class ServerComponentSerializer
 {
+    public const int PreambleBufferSize = 3;
+
     private readonly ITimeLimitedDataProtector _dataProtector;
 
     public ServerComponentSerializer(IDataProtectionProvider dataProtectionProvider) =>
@@ -45,49 +48,28 @@ public ServerComponentMarker SerializeInvocation(ServerComponentInvocationSequen
         return (serverComponent.Sequence, Convert.ToBase64String(protectedBytes));
     }
 
-    internal static IEnumerable<string> GetPreamble(ServerComponentMarker record)
+    /// <remarks>
+    /// Remember to update <see cref="PreambleBufferSize"/> if the number of entries being appended in this function changes.
+    /// </remarks>
+    internal static void AppendPreamble(IHtmlContentBuilder htmlContentBuilder, ServerComponentMarker record)
     {
         var serializedStartRecord = JsonSerializer.Serialize(
             record,
             ServerComponentSerializationSettings.JsonSerializationOptions);
 
-        if (record.PrerenderId != null)
-        {
-            return PrerenderedStart(serializedStartRecord);
-        }
-        else
-        {
-            return NonPrerenderedSequence(serializedStartRecord);
-        }
-
-        static IEnumerable<string> PrerenderedStart(string startRecord)
-        {
-            yield return "<!--Blazor:";
-            yield return startRecord;
-            yield return "-->";
-        }
-
-        static IEnumerable<string> NonPrerenderedSequence(string record)
-        {
-            yield return "<!--Blazor:";
-            yield return record;
-            yield return "-->";
-        }
+        htmlContentBuilder.AppendHtml("<!--Blazor:");
+        htmlContentBuilder.AppendHtml(serializedStartRecord);
+        htmlContentBuilder.AppendHtml("-->");
     }
 
-    internal static IEnumerable<string> GetEpilogue(ServerComponentMarker record)
+    internal static void AppendEpilogue(IHtmlContentBuilder htmlContentBuilder, ServerComponentMarker record)
     {
-        var serializedStartRecord = JsonSerializer.Serialize(
+        var endRecord = JsonSerializer.Serialize(
             record.GetEndRecord(),
             ServerComponentSerializationSettings.JsonSerializationOptions);
 
-        return PrerenderEnd(serializedStartRecord);
-
-        static IEnumerable<string> PrerenderEnd(string endRecord)
-        {
-            yield return "<!--Blazor:";
-            yield return endRecord;
-            yield return "-->";
-        }
+        htmlContentBuilder.AppendHtml("<!--Blazor:");
+        htmlContentBuilder.AppendHtml(endRecord);
+        htmlContentBuilder.AppendHtml("-->");
     }
 }
diff --git a/src/Mvc/Mvc.ViewFeatures/src/WebAssemblyComponentSerializer.cs b/src/Mvc/Mvc.ViewFeatures/src/WebAssemblyComponentSerializer.cs
index 343987834fca..d3c65401e026 100644
--- a/src/Mvc/Mvc.ViewFeatures/src/WebAssemblyComponentSerializer.cs
+++ b/src/Mvc/Mvc.ViewFeatures/src/WebAssemblyComponentSerializer.cs
@@ -3,6 +3,7 @@
 
 using System.Text.Json;
 using Microsoft.AspNetCore.Components;
+using Microsoft.AspNetCore.Mvc.ViewFeatures.Buffers;
 
 namespace Microsoft.AspNetCore.Mvc.ViewFeatures;
 
@@ -24,49 +25,25 @@ public static WebAssemblyComponentMarker SerializeInvocation(Type type, Paramete
             WebAssemblyComponentMarker.NonPrerendered(assembly, typeFullName, serializedDefinitions, serializedValues);
     }
 
-    internal static IEnumerable<string> GetPreamble(WebAssemblyComponentMarker record)
+    internal static void AppendPreamble(ViewBuffer viewBuffer, WebAssemblyComponentMarker record)
     {
         var serializedStartRecord = JsonSerializer.Serialize(
             record,
             WebAssemblyComponentSerializationSettings.JsonSerializationOptions);
 
-        if (record.PrerenderId != null)
-        {
-            return PrerenderedStart(serializedStartRecord);
-        }
-        else
-        {
-            return NonPrerenderedSequence(serializedStartRecord);
-        }
-
-        static IEnumerable<string> PrerenderedStart(string startRecord)
-        {
-            yield return "<!--Blazor:";
-            yield return startRecord;
-            yield return "-->";
-        }
-
-        static IEnumerable<string> NonPrerenderedSequence(string record)
-        {
-            yield return "<!--Blazor:";
-            yield return record;
-            yield return "-->";
-        }
+        viewBuffer.AppendHtml("<!--Blazor:");
+        viewBuffer.AppendHtml(serializedStartRecord);
+        viewBuffer.AppendHtml("-->");
     }
 
-    internal static IEnumerable<string> GetEpilogue(WebAssemblyComponentMarker record)
+    internal static void AppendEpilogue(ViewBuffer viewBuffer, WebAssemblyComponentMarker record)
     {
-        var serializedStartRecord = JsonSerializer.Serialize(
+        var endRecord = JsonSerializer.Serialize(
             record.GetEndRecord(),
             WebAssemblyComponentSerializationSettings.JsonSerializationOptions);
 
-        return PrerenderEnd(serializedStartRecord);
-
-        static IEnumerable<string> PrerenderEnd(string endRecord)
-        {
-            yield return "<!--Blazor:";
-            yield return endRecord;
-            yield return "-->";
-        }
+        viewBuffer.AppendHtml("<!--Blazor:");
+        viewBuffer.AppendHtml(endRecord);
+        viewBuffer.AppendHtml("-->");
     }
 }
diff --git a/src/Mvc/Mvc.ViewFeatures/test/RazorComponents/ComponentRendererTest.cs b/src/Mvc/Mvc.ViewFeatures/test/RazorComponents/ComponentRendererTest.cs
index 4fbe4842cb1b..b6225d5c05fc 100644
--- a/src/Mvc/Mvc.ViewFeatures/test/RazorComponents/ComponentRendererTest.cs
+++ b/src/Mvc/Mvc.ViewFeatures/test/RazorComponents/ComponentRendererTest.cs
@@ -11,6 +11,7 @@
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Mvc.Rendering;
+using Microsoft.AspNetCore.Mvc.ViewFeatures.Buffers;
 using Microsoft.AspNetCore.Testing;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
@@ -292,7 +293,7 @@ public async Task CanRender_ParameterlessComponent_ServerMode()
 
         // Act
         var result = await renderer.RenderComponentAsync(viewContext, typeof(TestComponent), RenderMode.Server, null);
-        var content = HtmlContentUtilities.HtmlContentToString(result);
+        var content = HtmlContentUtilities.HtmlContentToString(result, HtmlEncoder.Default);
         var match = Regex.Match(content, ComponentPattern);
 
         // Assert
@@ -324,7 +325,7 @@ public async Task CanPrerender_ParameterlessComponent_ServerMode()
 
         // Act
         var result = await renderer.RenderComponentAsync(viewContext, typeof(TestComponent), RenderMode.ServerPrerendered, null);
-        var content = HtmlContentUtilities.HtmlContentToString(result);
+        var content = HtmlContentUtilities.HtmlContentToString(result, HtmlEncoder.Default);
         var match = Regex.Match(content, PrerenderedComponentPattern, RegexOptions.Multiline);
 
         // Assert
@@ -426,7 +427,7 @@ public async Task CanRender_ComponentWithParametersObject()
         var result = await renderer.RenderComponentAsync(viewContext, typeof(GreetingComponent), RenderMode.Static, new { Name = "Steve" });
 
         // Assert
-        var content = HtmlContentUtilities.HtmlContentToString(result);
+        var content = HtmlContentUtilities.HtmlContentToString(result, HtmlEncoder.Default);
         Assert.Equal("<p>Hello Steve!</p>", content);
     }
 
@@ -440,7 +441,7 @@ public async Task CanRender_ComponentWithParameters_ServerMode()
 
         // Act
         var result = await renderer.RenderComponentAsync(viewContext, typeof(GreetingComponent), RenderMode.Server, new { Name = "Daniel" });
-        var content = HtmlContentUtilities.HtmlContentToString(result);
+        var content = HtmlContentUtilities.HtmlContentToString(result, HtmlEncoder.Default);
         var match = Regex.Match(content, ComponentPattern);
 
         // Assert
@@ -479,7 +480,7 @@ public async Task CanRender_ComponentWithNullParameters_ServerMode()
         // Act
 
         var result = await renderer.RenderComponentAsync(viewContext, typeof(GreetingComponent), RenderMode.Server, new { Name = (string)null });
-        var content = HtmlContentUtilities.HtmlContentToString(result);
+        var content = HtmlContentUtilities.HtmlContentToString(result, HtmlEncoder.Default);
         var match = Regex.Match(content, ComponentPattern);
 
         // Assert
@@ -518,7 +519,7 @@ public async Task CanPrerender_ComponentWithParameters_ServerPrerenderedMode()
 
         // Act
         var result = await renderer.RenderComponentAsync(viewContext, typeof(GreetingComponent), RenderMode.ServerPrerendered, new { Name = "Daniel" });
-        var content = HtmlContentUtilities.HtmlContentToString(result);
+        var content = HtmlContentUtilities.HtmlContentToString(result, HtmlEncoder.Default);
         var match = Regex.Match(content, PrerenderedComponentPattern, RegexOptions.Multiline);
 
         // Assert
@@ -569,7 +570,7 @@ public async Task CanPrerender_ComponentWithNullParameters_ServerPrerenderedMode
 
         // Act
         var result = await renderer.RenderComponentAsync(viewContext, typeof(GreetingComponent), RenderMode.ServerPrerendered, new { Name = (string)null });
-        var content = HtmlContentUtilities.HtmlContentToString(result);
+        var content = HtmlContentUtilities.HtmlContentToString(result, HtmlEncoder.Default);
         var match = Regex.Match(content, PrerenderedComponentPattern, RegexOptions.Multiline);
 
         // Assert
@@ -617,7 +618,7 @@ public async Task ComponentWithInvalidRenderMode_Throws()
 
         // Act & Assert
         var ex = await ExceptionAssert.ThrowsArgumentAsync(
-            () => renderer.RenderComponentAsync(viewContext, typeof(GreetingComponent), default, new { Name = "Daniel" }),
+            async () => await renderer.RenderComponentAsync(viewContext, typeof(GreetingComponent), default, new { Name = "Daniel" }),
             "renderMode",
             $"Unsupported RenderMode '{(RenderMode)default}'");
     }
@@ -633,7 +634,7 @@ public async Task RenderComponent_DoesNotInvokeOnAfterRenderInComponent()
         var result = await renderer.RenderComponentAsync(viewContext, typeof(OnAfterRenderComponent), RenderMode.Static, new { state });
 
         // Assert
-        var content = HtmlContentUtilities.HtmlContentToString(result);
+        var content = HtmlContentUtilities.HtmlContentToString(result, HtmlEncoder.Default);
         Assert.Equal("<p>Hello</p>", content);
         Assert.False(state.OnAfterRenderRan);
     }
@@ -651,6 +652,7 @@ public async Task DisposableComponents_GetDisposedAfterScopeCompletes()
         collection.TryAddSingleton<ServerComponentSerializer>();
         collection.TryAddSingleton(_dataprotectorProvider);
         collection.TryAddSingleton<WebAssemblyComponentSerializer>();
+        collection.TryAddScoped<IViewBufferScope, TestViewBufferScope>();
 
         var provider = collection.BuildServiceProvider();
         var scope = provider.GetRequiredService<IServiceScopeFactory>().CreateScope();
@@ -664,7 +666,7 @@ public async Task DisposableComponents_GetDisposedAfterScopeCompletes()
         var result = await renderer.RenderComponentAsync(viewContext, typeof(AsyncDisposableComponent), RenderMode.Static, new { state });
 
         // Assert
-        var content = HtmlContentUtilities.HtmlContentToString(result);
+        var content = HtmlContentUtilities.HtmlContentToString(result, HtmlEncoder.Default);
         Assert.Equal("<p>Hello</p>", content);
         await ((IAsyncDisposable)scope).DisposeAsync();
 
@@ -678,7 +680,7 @@ public async Task CanCatch_ComponentWithSynchronousException()
         var viewContext = GetViewContext();
 
         // Act & Assert
-        var exception = await Assert.ThrowsAsync<InvalidOperationException>(() => renderer.RenderComponentAsync(
+        var exception = await Assert.ThrowsAsync<InvalidOperationException>(async () => await renderer.RenderComponentAsync(
             viewContext,
             typeof(ExceptionComponent),
             RenderMode.Static,
@@ -698,7 +700,7 @@ public async Task CanCatch_ComponentWithAsynchronousException()
         var viewContext = GetViewContext();
 
         // Act & Assert
-        var exception = await Assert.ThrowsAsync<InvalidOperationException>(() => renderer.RenderComponentAsync(
+        var exception = await Assert.ThrowsAsync<InvalidOperationException>(async () => await renderer.RenderComponentAsync(
             viewContext,
             typeof(ExceptionComponent),
             RenderMode.Static,
@@ -718,7 +720,7 @@ public async Task Rendering_ComponentWithJsInteropThrows()
         var viewContext = GetViewContext();
 
         // Act & Assert
-        var exception = await Assert.ThrowsAsync<InvalidOperationException>(() => renderer.RenderComponentAsync(
+        var exception = await Assert.ThrowsAsync<InvalidOperationException>(async () => await renderer.RenderComponentAsync(
             viewContext,
             typeof(ExceptionComponent),
             RenderMode.Static,
@@ -751,7 +753,7 @@ public async Task UriHelperRedirect_ThrowsInvalidOperationException_WhenResponse
         var viewContext = GetViewContext(ctx);
 
         // Act
-        var exception = await Assert.ThrowsAsync<InvalidOperationException>(() => renderer.RenderComponentAsync(
+        var exception = await Assert.ThrowsAsync<InvalidOperationException>(async () => await renderer.RenderComponentAsync(
             viewContext,
             typeof(RedirectComponent),
             RenderMode.Static,
@@ -843,17 +845,20 @@ public async Task CanRender_AsyncComponent()
 
         // Act
         var result = await renderer.RenderComponentAsync(viewContext, typeof(AsyncComponent), RenderMode.Static, null);
-        var content = HtmlContentUtilities.HtmlContentToString(result);
+        var content = HtmlContentUtilities.HtmlContentToString(result, HtmlEncoder.Default);
 
         // Assert
         Assert.Equal(expectedContent.Replace("\r\n", "\n"), content);
     }
 
-    private ComponentRenderer GetComponentRenderer(IServiceProvider services = null) =>
-        new ComponentRenderer(
-            new StaticComponentRenderer(new HtmlRenderer(services ?? _services, NullLoggerFactory.Instance, HtmlEncoder.Default)),
+    private ComponentRenderer GetComponentRenderer(IServiceProvider services = null)
+    {
+        var viewBufferScope = new TestViewBufferScope();
+        return new ComponentRenderer(
+            new StaticComponentRenderer(new HtmlRenderer(services ?? _services, NullLoggerFactory.Instance, viewBufferScope)),
             new ServerComponentSerializer(_dataprotectorProvider),
-            new WebAssemblyComponentSerializer());
+            viewBufferScope);
+    }
 
     private ViewContext GetViewContext(HttpContext context = null)
     {
diff --git a/src/Mvc/Mvc.ViewFeatures/test/RazorComponents/HtmlRendererTest.cs b/src/Mvc/Mvc.ViewFeatures/test/RazorComponents/HtmlRendererTest.cs
index 0cfcf4755470..c8845c0de376 100644
--- a/src/Mvc/Mvc.ViewFeatures/test/RazorComponents/HtmlRendererTest.cs
+++ b/src/Mvc/Mvc.ViewFeatures/test/RazorComponents/HtmlRendererTest.cs
@@ -4,6 +4,9 @@
 using System.Globalization;
 using System.Runtime.ExceptionServices;
 using System.Text.Encodings.Web;
+using Microsoft.AspNetCore.Html;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.ViewFeatures.Buffers;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging.Abstractions;
 
@@ -29,7 +32,7 @@ public void RenderComponentAsync_CanRenderEmptyElement()
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, result);
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
     [Fact]
@@ -49,7 +52,7 @@ public void RenderComponentAsync_CanRenderSimpleComponent()
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, result);
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
     [Fact]
@@ -69,7 +72,7 @@ public void RenderComponentAsync_HtmlEncodesContent()
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, result);
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
 
@@ -90,7 +93,7 @@ public void RenderComponentAsync_DoesNotEncodeMarkup()
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, result);
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
     [Fact]
@@ -112,7 +115,7 @@ public void RenderComponentAsync_CanRenderWithAttributes()
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, result);
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
     [Fact]
@@ -146,7 +149,7 @@ public void RenderComponentAsync_SkipsDuplicatedAttribute()
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, result);
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
     [Fact]
@@ -168,7 +171,7 @@ public void RenderComponentAsync_HtmlEncodesAttributeValues()
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, result);
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
     [Fact]
@@ -189,7 +192,7 @@ public void RenderComponentAsync_CanRenderBooleanAttributes()
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, result);
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
     [Fact]
@@ -210,7 +213,7 @@ public void RenderComponentAsync_DoesNotRenderBooleanAttributesWhenValueIsFalse(
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, result);
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
     [Fact]
@@ -233,7 +236,7 @@ public void RenderComponentAsync_CanRenderWithChildren()
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, result);
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
     [Fact]
@@ -263,7 +266,7 @@ public void RenderComponentAsync_CanRenderWithMultipleChildren()
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, result);
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
     [Fact]
@@ -311,7 +314,7 @@ public void RenderComponentAsync_MarksSelectedOptionsAsSelected()
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, string.Concat(result));
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
     [Fact]
@@ -348,7 +351,7 @@ public void RenderComponentAsync_MarksSelectedOptionsAsSelected_WithOptGroups()
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, string.Concat(result));
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
     [Fact]
@@ -377,7 +380,7 @@ public void RenderComponentAsync_CanRenderComponentAsyncWithChildrenComponents()
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, result);
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
     [Fact]
@@ -407,7 +410,7 @@ public void RenderComponentAsync_ComponentReferenceNoops()
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, result);
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
     [Fact]
@@ -443,7 +446,7 @@ public void RenderComponentAsync_CanPassParameters()
             }))));
 
         // Assert
-        Assert.Equal(expectedHtml, result);
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
     [Fact]
@@ -469,15 +472,17 @@ public void RenderComponentAsync_CanRenderComponentAsyncWithRenderFragmentConten
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, result);
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
     [Fact]
     public void RenderComponentAsync_ElementRefsNoops()
     {
         // Arrange
-        var expectedHtml = new[] {
-                "<", "p", ">", "<", "span", ">", "Hello world!", "</", "span", ">", "</", "p", ">" };
+        var expectedHtml = new[]
+        {
+            "<", "p", ">", "<", "span", ">", "Hello world!", "</", "span", ">", "</", "p", ">"
+        };
         var serviceProvider = new ServiceCollection().AddSingleton(new RenderFragment(rtb =>
         {
             rtb.OpenElement(0, "p");
@@ -496,15 +501,15 @@ public void RenderComponentAsync_ElementRefsNoops()
         var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
         // Assert
-        Assert.Equal(expectedHtml, result);
+        AssertHtmlContentEquals(expectedHtml, result);
     }
 
-    private IEnumerable<string> GetResult(Task<ComponentRenderedText> task)
+    private IHtmlContent GetResult(Task<ComponentRenderedText> task)
     {
         Assert.True(task.IsCompleted);
         if (task.IsCompletedSuccessfully)
         {
-            return task.Result.Tokens;
+            return task.Result.HtmlContent;
         }
         else
         {
@@ -513,6 +518,17 @@ private IEnumerable<string> GetResult(Task<ComponentRenderedText> task)
         }
     }
 
+    private void AssertHtmlContentEquals(IEnumerable<string> expected, IHtmlContent actual)
+    {
+        var expectedString = string.Concat(expected);
+        AssertHtmlContentEquals(expectedString, actual);
+    }
+
+    private void AssertHtmlContentEquals(string expected, IHtmlContent actual)
+    {
+        Assert.Equal(expected, HtmlContentUtilities.HtmlContentToString(actual, _encoder));
+    }
+
     private class ComponentWithParameters : IComponent
     {
         public RenderHandle RenderHandle { get; private set; }
@@ -549,7 +565,7 @@ public async Task CanRender_AsyncComponent()
         })));
 
         // Assert
-        Assert.Equal(expectedHtml, result.Tokens);
+        AssertHtmlContentEquals(expectedHtml, result.HtmlContent);
     }
 
     [Fact]
@@ -574,7 +590,7 @@ public async Task CanRender_NestedAsyncComponents()
         })));
 
         // Assert
-        Assert.Equal(expectedHtml, result.Tokens);
+        AssertHtmlContentEquals(expectedHtml, result.HtmlContent);
     }
 
     [Fact]
@@ -600,7 +616,7 @@ public async Task PrerendersMultipleComponentsSuccessfully()
 
     private HtmlRenderer GetHtmlRenderer(IServiceProvider serviceProvider)
     {
-        return new HtmlRenderer(serviceProvider, NullLoggerFactory.Instance, _encoder);
+        return new HtmlRenderer(serviceProvider, NullLoggerFactory.Instance, new TestViewBufferScope());
     }
 
     private class NestedAsyncComponent : ComponentBase
diff --git a/src/Mvc/Mvc.ViewFeatures/test/Rendering/HtmlHelperComponentExtensionsTest.cs b/src/Mvc/Mvc.ViewFeatures/test/Rendering/HtmlHelperComponentExtensionsTest.cs
index e4b82574bd65..4e6b65a13b1a 100644
--- a/src/Mvc/Mvc.ViewFeatures/test/Rendering/HtmlHelperComponentExtensionsTest.cs
+++ b/src/Mvc/Mvc.ViewFeatures/test/Rendering/HtmlHelperComponentExtensionsTest.cs
@@ -1,4 +1,4 @@
-// Licensed to the .NET Foundation under one or more agreements.
+// Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using Microsoft.AspNetCore.Components;
@@ -30,7 +30,7 @@ private static ViewContext GetViewContext()
     {
         var htmlContent = new HtmlContentBuilder().AppendHtml("Hello world");
         var renderer = Mock.Of<IComponentRenderer>(c =>
-            c.RenderComponentAsync(It.IsAny<ViewContext>(), It.IsAny<Type>(), It.IsAny<RenderMode>(), It.IsAny<object>()) == Task.FromResult<IHtmlContent>(htmlContent));
+            c.RenderComponentAsync(It.IsAny<ViewContext>(), It.IsAny<Type>(), It.IsAny<RenderMode>(), It.IsAny<object>()) == new ValueTask<IHtmlContent>(htmlContent));
 
         var httpContext = new DefaultHttpContext
         {