Pages that are re-executed should allow interactivity (#63964)

Author: ilonatommy

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

@@ -20,7 +20,7 @@ internal partial class EndpointHtmlRenderer
 
     protected override IComponent ResolveComponentForRenderMode([DynamicallyAccessedMembers(Component)] Type componentType, int? parentComponentId, IComponentActivator componentActivator, IComponentRenderMode renderMode)
     {
-        if (_isHandlingErrors || _isReExecuted)
+        if (_isHandlingErrors)
         {
             // Ignore the render mode boundary in error scenarios.
             return componentActivator.CreateInstance(componentType);

src/Components/test/E2ETest/ServerRenderingTests/InteractivityTest.cs

@@ -1515,6 +1515,24 @@ public void BrowserNavigationToNotExistingPathReExecutesTo404(string renderMode)
         Assert404ReExecuted();
     }
 
+    [Fact]
+    public void BrowserNavigationToNotExistingPathReExecutesTo404_Interactive()
+    {
+        // non-existing path has to have re-execution middleware set up
+        // so it has to have "interactive-reexecution" prefix. Otherwise middleware mapping
+        // will not be activated, see configuration in Startup
+        Navigate($"{ServerPathBase}/interactive-reexecution/not-existing-page");
+        Assert404ReExecuted();
+        AssertReExecutedPageIsInteractive();
+    }
+
+    private void AssertReExecutedPageIsInteractive()
+    {
+        Browser.Equal("Current count: 0", () => Browser.FindElement(By.CssSelector("[role='status']")).Text);
+        Browser.Click(By.Id("increment-button"));
+        Browser.Equal("Current count: 1", () => Browser.FindElement(By.CssSelector("[role='status']")).Text);
+    }
+
     private void Assert404ReExecuted() =>
         Browser.Equal("Welcome On Page Re-executed After Not Found Event", () => Browser.Exists(By.Id("test-info")).Text);
 }

src/Components/test/testassets/Components.TestServer/RazorComponentEndpointsStartup.cs

@@ -109,6 +109,13 @@ public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
                 reexecutionApp.UseAntiforgery();
                 ConfigureEndpoints(reexecutionApp, env);
             });
+            app.Map("/interactive-reexecution", reexecutionApp =>
+            {
+                reexecutionApp.UseStatusCodePagesWithReExecute("/not-found-reexecute-interactive", createScopeForStatusCodePages: true);
+                reexecutionApp.UseRouting();
+                reexecutionApp.UseAntiforgery();
+                ConfigureEndpoints(reexecutionApp, env);
+            });
 
             ConfigureSubdirPipeline(app, env);
         });

src/Components/test/testassets/TestContentPackage/NotFound/ReExecutedComponent.razor

@@ -0,0 +1,4 @@
+<PageTitle>Re-executed page</PageTitle>
+
+<h3 id="test-info">Welcome On Page Re-executed After Not Found Event</h3>
+<p>This page is shown when UseStatusCodePagesWithReExecute is set and another page sets 404</p>

src/Components/test/testassets/TestContentPackage/NotFound/ReexecutedPage.razor

@@ -1,6 +1,3 @@
 @page "/not-found-reexecute"
 
-<PageTitle>Re-executed page</PageTitle>
-
-<h3 id="test-info">Welcome On Page Re-executed After Not Found Event</h3>
-<p>This page is shown when UseStatusCodePagesWithReExecute is set and another page sets 404</p>
+<ReExecutedComponent />

src/Components/test/testassets/TestContentPackage/NotFound/ReexecutedPageInteractive.razor

@@ -0,0 +1,17 @@
+@page "/not-found-reexecute-interactive"
+@rendermode RenderMode.InteractiveServer
+
+<ReExecutedComponent />
+
+<p role="status">Current count: @currentCount</p>
+
+<button id="increment-button" class="btn btn-primary" @onclick="IncrementCount">Click me</button>
+
+@code {
+    private int currentCount = 0;
+
+    private void IncrementCount()
+    {
+        currentCount++;
+    }
+}