More tests

src/Components/Endpoints/src/RazorComponentEndpointInvoker.cs

@@ -4,7 +4,6 @@
 using System.Buffers;
 using System.Text;
 using System.Text.Encodings.Web;
-using Microsoft.AspNetCore.Components.Web.HtmlRendering;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.WebUtilities;
 using Microsoft.Extensions.DependencyInjection;

src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs

@@ -121,6 +121,11 @@ protected override void TrackNamedEventId(ulong eventHandlerId, int componentId,
 
     internal Task DispatchCapturedEvent()
     {
+        if (_capturedNamedEvent == default)
+        {
+            throw new InvalidOperationException($"No named event handler was captured for '{_formHandler}'.");
+        }
+
         // Clear the list of non-streaming rendering tasks, since we've waited for quiesce before dispatching the event.
         _nonStreamingPendingTasks.Clear();
         return DispatchEventAsync(_capturedNamedEvent.EventHandlerId, null, EventArgs.Empty, quiesce: true);

src/Components/Endpoints/test/EndpointHtmlRendererTest.cs

@@ -812,7 +812,7 @@ public async Task CanRender_AsyncComponent()
     }
 
     [Fact]
-    public void DuplicateNamedEventHandlersAcrossComponentsThrows()
+    public void Duplicate_NamedEventHandlers_AcrossComponents_Throws()
     {
         // Arrange
         var expectedError = @"Two different components are trying to define the same named event 'default':
@@ -873,6 +873,97 @@ public void RecreatedComponent_AcrossDifferentBatches_WithNamedEventHandler_Thro
         Assert.Equal(expectedError, exception.Message);
     }
 
+    [Fact]
+    public void SameComponent_WithNamedEvent_CanRenderSynchronously_MultipleTimes()
+    {
+        // Arrange
+        var renderer = GetEndpointHtmlRenderer();
+        renderer.SetFormHandlerName("default");
+
+        var component = new TestComponent(builder =>
+        {
+            builder.OpenComponent<MultiRenderNamedEventHandlerComponent>(0);
+            builder.CloseComponent();
+        });
+
+        // Act
+        var componentId = renderer.TestAssignRootComponentId(component);
+        renderer.Dispatcher.InvokeAsync(component.TriggerRender);
+
+        // Assert
+        Assert.Equal(2, renderer.TrackedNamedEvents.Count);
+    }
+
+    [Fact]
+    public async Task SameComponent_WithNamedEvent_CanRenderAsynchronously_MultipleTimes()
+    {
+        // Arrange
+        var renderer = GetEndpointHtmlRenderer();
+        renderer.SetFormHandlerName("default");
+        var continueTaskCompletion = new TaskCompletionSource();
+
+        // Act
+        var result = await renderer.Dispatcher.InvokeAsync(() => renderer.BeginRenderingComponent(
+            typeof(MultiAsyncRenderNamedEventHandlerComponent),
+            ParameterView.FromDictionary(new Dictionary<string, object>
+            {
+                [nameof(MultiAsyncRenderNamedEventHandlerComponent.Continue)] = continueTaskCompletion.Task
+            })));
+
+        // Assert
+        continueTaskCompletion.SetResult();
+        await result.QuiescenceTask;
+        Assert.Equal(2, renderer.TrackedNamedEvents.Count);
+    }
+
+    [Fact]
+    public async Task CanDispatchNamedEvent_ToComponent()
+    {
+        // Arrange
+        var renderer = GetEndpointHtmlRenderer();
+        renderer.SetFormHandlerName("default");
+        var continueTaskCompletion = new TaskCompletionSource();
+        var invoked = false;
+        Action handler = () => invoked = true;
+        await renderer.Dispatcher.InvokeAsync(async () =>
+        {
+            var result = renderer.BeginRenderingComponent(
+                typeof(NamedEventHandlerComponent),
+                ParameterView.FromDictionary(new Dictionary<string, object>
+                {
+                    [nameof(NamedEventHandlerComponent.Handler)] = handler
+                }));
+
+            await result.QuiescenceTask;
+
+            // Act
+            await renderer.DispatchCapturedEvent();
+        });
+
+        // Assert
+        Assert.True(invoked);
+    }
+
+    [Fact]
+    public async Task Dispatching_WhenEventHasNotBeenFound_Throws()
+    {
+        // Arrange
+        var renderer = GetEndpointHtmlRenderer();
+        renderer.SetFormHandlerName("other");
+
+        var exception = await Assert.ThrowsAsync<InvalidOperationException>(() =>
+            renderer.Dispatcher.InvokeAsync(async () =>
+            {
+                var result = renderer.BeginRenderingComponent(typeof(NamedEventHandlerComponent), ParameterView.Empty);
+                await result.QuiescenceTask;
+
+                // Act
+                await renderer.DispatchCapturedEvent();
+            }));
+
+        Assert.Equal("No named event handler was captured for 'other'.", exception.Message);
+    }
+
     [Fact]
     public void NamedEventHandlers_DifferentComponents_SameNamedHandlerInDifferentBatches_Throws()
     {
@@ -917,15 +1008,73 @@ public void NamedEventHandlers_DifferentComponents_SameNamedHandlerInDifferentBa
 
     private class NamedEventHandlerComponent : ComponentBase
     {
+        [Parameter]
+        public Action Handler { get; set; }
+
         protected override void BuildRenderTree(RenderTreeBuilder builder)
         {
             builder.OpenElement(0, "form");
-            builder.AddAttribute(1, "onsubmit", () => { });
+            builder.AddAttribute(1, "onsubmit", Handler ?? (() => { }));
             builder.SetEventHandlerName("default");
             builder.CloseElement();
         }
     }
 
+    private class MultiRenderNamedEventHandlerComponent : ComponentBase
+    {
+        private bool hasRendered;
+
+        protected override void BuildRenderTree(RenderTreeBuilder builder)
+        {
+            builder.OpenElement(0, "form");
+            if (!hasRendered)
+            {
+                builder.AddAttribute(1, "onsubmit", () => { });
+                builder.SetEventHandlerName("default");
+            }
+            else
+            {
+                builder.AddAttribute(1, "onsubmit", () => { GC.KeepAlive(new object()); });
+                builder.SetEventHandlerName("default");
+            }
+            builder.CloseElement();
+            if (!hasRendered)
+            {
+                hasRendered = true;
+                StateHasChanged();
+            }
+        }
+    }
+
+    private class MultiAsyncRenderNamedEventHandlerComponent : ComponentBase
+    {
+        private bool hasRendered;
+
+        [Parameter] public Task Continue { get; set; }
+
+        protected override void BuildRenderTree(RenderTreeBuilder builder)
+        {
+            builder.OpenElement(0, "form");
+            if (!hasRendered)
+            {
+                builder.AddAttribute(1, "onsubmit", () => { });
+                builder.SetEventHandlerName("default");
+            }
+            else
+            {
+                builder.AddAttribute(1, "onsubmit", () => { GC.KeepAlive(new object()); });
+                builder.SetEventHandlerName("default");
+            }
+            builder.CloseElement();
+        }
+
+        protected override async Task OnInitializedAsync()
+        {
+            await Continue;
+            hasRendered = true;
+        }
+    }
+
     private class OtherNamedEventHandlerComponent : ComponentBase
     {
         protected override void BuildRenderTree(RenderTreeBuilder builder)
@@ -973,6 +1122,16 @@ internal int TestAssignRootComponentId(IComponent component)
         {
             return base.AssignRootComponentId(component);
         }
+
+        protected override void TrackNamedEventId(ulong eventHandlerId, int componentId, string eventNameId)
+        {
+            TrackedNamedEvents.Add(new TrackedNamedEvent(eventHandlerId, componentId, eventNameId));
+            base.TrackNamedEventId(eventHandlerId, componentId, eventNameId);
+        }
+
+        public List<TrackedNamedEvent> TrackedNamedEvents { get; set; } = new List<TrackedNamedEvent>();
+
+        public readonly record struct TrackedNamedEvent(ulong EventHandlerId, int ComponentId, string EventNameId);
     }
 
     private HttpContext GetHttpContext(HttpContext context = null)

src/Components/Web/src/PublicAPI.Unshipped.txt

@@ -1,6 +1,6 @@
 #nullable enable
 *REMOVED*override Microsoft.AspNetCore.Components.Forms.InputFile.OnInitialized() -> void
-Microsoft.AspNetCore.Components.Forms.EditForm.BindingContext.get -> Microsoft.AspNetCore.Components.Binding.ModelBindingContext!
+Microsoft.AspNetCore.Components.Forms.EditForm.BindingContext.get -> Microsoft.AspNetCore.Components.Binding.ModelBindingContext?
 Microsoft.AspNetCore.Components.Forms.EditForm.BindingContext.set -> void
 Microsoft.AspNetCore.Components.HtmlRendering.Infrastructure.StaticHtmlRenderer
 Microsoft.AspNetCore.Components.HtmlRendering.Infrastructure.StaticHtmlRenderer.BeginRenderingComponent(System.Type! componentType, Microsoft.AspNetCore.Components.ParameterView initialParameters) -> Microsoft.AspNetCore.Components.Web.HtmlRendering.HtmlRootComponent