Improve renderer unit test

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

@@ -183,7 +183,8 @@ protected override void AddPendingTask(ComponentState? componentState, Task task
         base.AddPendingTask(componentState, task);
     }
 
-    private void SignalRendererToFinishRendering()
+    // For testing purposes only
+    internal void SignalRendererToFinishRendering()
     {
         // sets a deferred stop on the renderer, which will have an effect after the current batch is completed
         _rendererIsStopped = true;

src/Components/Endpoints/test/EndpointHtmlRendererTest.cs

@@ -11,6 +11,7 @@
 using Microsoft.AspNetCore.Components.Infrastructure;
 using Microsoft.AspNetCore.Components.Reflection;
 using Microsoft.AspNetCore.Components.Rendering;
+using Microsoft.AspNetCore.Components.RenderTree;
 using Microsoft.AspNetCore.Components.Test.Helpers;
 using Microsoft.AspNetCore.Components.Web;
 using Microsoft.AspNetCore.DataProtection;
@@ -47,18 +48,23 @@ public EndpointHtmlRendererTest()
     }
 
     [Fact]
-    public async Task DoesNotRenderChildAfterRendererStopped()
+    public async Task DoesNotRenderAfterRendererStopped()
     {
-        renderer.SignalRendererToFinishRendering();
-
         var httpContext = GetHttpContext();
         var writer = new StringWriter();
 
-        var result = await renderer.PrerenderComponentAsync(httpContext, typeof(SimpleComponent), null, ParameterView.Empty);
-        await renderer.Dispatcher.InvokeAsync(() => result.WriteTo(writer, HtmlEncoder.Default));
-        var content = writer.ToString();
+        var component = new StoppingRendererComponent();
+        var id = renderer.AssignRootComponentId(component);
+        var initialRenderOperation = renderer.Dispatcher.InvokeAsync(
+            () => renderer.RenderRootComponentAsync(id, ParameterView.Empty));
 
-        Assert.DoesNotContain("Hello from SimpleComponent", content);
+        renderer.SignalRendererToFinishRendering();
+        component.TaskCompletionSource.SetResult(false);
+        await initialRenderOperation;
+        int initialRenderCount = renderer.RenderCount;
+
+        await renderer.Dispatcher.InvokeAsync(() => renderer.RenderRootComponentAsync(id, ParameterView.Empty));
+        Assert.Equal(initialRenderCount, renderer.RenderCount);
     }
 
     [Fact]
@@ -1772,18 +1778,10 @@ private TestEndpointHtmlRenderer GetEndpointHtmlRenderer(IServiceProvider servic
     private class TestEndpointHtmlRenderer : EndpointHtmlRenderer
     {
         private bool _rendererIsStopped = false;
-        public TestEndpointHtmlRenderer(IServiceProvider serviceProvider, ILoggerFactory loggerFactory) : base(serviceProvider, loggerFactory)
-        {
-        }
+        private int _renderCount;
 
-        internal int TestAssignRootComponentId(IComponent component)
+        public TestEndpointHtmlRenderer(IServiceProvider serviceProvider, ILoggerFactory loggerFactory) : base(serviceProvider, loggerFactory)
         {
-            return base.AssignRootComponentId(component);
-        }
-        public void SignalRendererToFinishRendering()
-        {
-            // sets a deferred stop on the renderer, which will have an effect after the current batch is completed
-            _rendererIsStopped = true;
         }
 
         protected override void ProcessPendingRender()
@@ -1793,6 +1791,16 @@ protected override void ProcessPendingRender()
                 return;
             }
             base.ProcessPendingRender();
+
+            _renderCount++;
+        }
+
+        public int RenderCount => _renderCount;
+
+        public new void SignalRendererToFinishRendering()
+        {
+            _rendererIsStopped = true;
+            base.SignalRendererToFinishRendering();
         }
     }
 

src/Components/Endpoints/test/TestComponents/StoppingRendererComponent.razor

@@ -0,0 +1,17 @@
+<h1>Hello from StoppingRendererComponent</h1>
+<p>State is @_state</p>
+
+@code {
+    private bool _state = true;
+
+    // expose a TCS so the test can control when OnInitializedAsync completes
+    public TaskCompletionSource<bool> TaskCompletionSource = new TaskCompletionSource<bool>();
+
+    protected override async Task OnInitializedAsync()
+    {
+        // wait until the test signals
+        var result = await TaskCompletionSource.Task;
+        _state = result;
+        StateHasChanged();
+    }
+}

src/Components/Server/src/Circuits/RemoteNavigationManager.cs

@@ -19,7 +19,7 @@ internal sealed partial class RemoteNavigationManager : NavigationManager, IHost
     private bool? _navigationLockStateBeforeJsRuntimeAttached;
     private const string _enableThrowNavigationException = "Microsoft.AspNetCore.Components.Endpoints.NavigationManager.EnableThrowNavigationException";
 
-    [FeatureSwitchDefinition("Microsoft.AspNetCore.Components.Endpoints.NavigationManager.EnableThrowNavigationException")]
+    [FeatureSwitchDefinition(_enableThrowNavigationException)]
     private static bool _throwNavigationException =>
         AppContext.TryGetSwitch(_enableThrowNavigationException, out var switchValue) && switchValue;
     private Func<string, Task>? _onNavigateTo;