Add custom serializer support to E2E tests for persistent component state

Co-authored-by: javiercn <[email protected]>

Author: Copilot

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

@@ -1059,6 +1059,7 @@ public void CanPersistPrerenderedStateDeclaratively_Server()
         Navigate($"{ServerPathBase}/persist-state?server=true&declarative=true");
 
         Browser.Equal("restored", () => Browser.FindElement(By.Id("server")).Text);
+        Browser.Equal("42", () => Browser.FindElement(By.Id("custom-server")).Text);
         Browser.Equal("Server", () => Browser.FindElement(By.Id("render-mode-server")).Text);
     }
 
@@ -1077,6 +1078,7 @@ public void CanPersistPrerenderedStateDeclaratively_WebAssembly()
         Navigate($"{ServerPathBase}/persist-state?wasm=true&declarative=true");
 
         Browser.Equal("restored", () => Browser.FindElement(By.Id("wasm")).Text);
+        Browser.Equal("42", () => Browser.FindElement(By.Id("custom-wasm")).Text);
         Browser.Equal("WebAssembly", () => Browser.FindElement(By.Id("render-mode-wasm")).Text);
     }
 
@@ -1095,6 +1097,7 @@ public void CanPersistPrerenderedStateDeclaratively_Auto_PersistsOnWebAssembly()
         Navigate($"{ServerPathBase}/persist-state?auto=true&declarative=true");
 
         Browser.Equal("restored", () => Browser.FindElement(By.Id("auto")).Text);
+        Browser.Equal("42", () => Browser.FindElement(By.Id("custom-auto")).Text);
         Browser.Equal("WebAssembly", () => Browser.FindElement(By.Id("render-mode-auto")).Text);
     }
 
@@ -1156,6 +1159,7 @@ public void CanPersistPrerenderedStateDeclaratively_Auto_PersistsOnServer()
         Navigate($"{ServerPathBase}/persist-state?auto=true&declarative=true");
 
         Browser.Equal("restored", () => Browser.FindElement(By.Id("auto")).Text);
+        Browser.Equal("42", () => Browser.FindElement(By.Id("custom-auto")).Text);
         Browser.Equal("Server", () => Browser.FindElement(By.Id("render-mode-auto")).Text);
     }
 

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

@@ -0,0 +1,37 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Buffers;
+using System.Text;
+using Microsoft.AspNetCore.Components;
+
+namespace TestServer;
+
+/// <summary>
+/// A custom serializer for int values that uses a custom format to test serialization extensibility.
+/// This serializer prefixes integer values with "CUSTOM:" to clearly distinguish them from JSON serialization.
+/// </summary>
+public class CustomIntSerializer : IPersistentComponentStateSerializer<int>
+{
+    public Task PersistAsync(int value, IBufferWriter<byte> writer)
+    {
+        var customFormat = $"CUSTOM:{value}";
+        var bytes = Encoding.UTF8.GetBytes(customFormat);
+        writer.Write(bytes);
+        return Task.CompletedTask;
+    }
+
+    public int Restore(ReadOnlySequence<byte> data)
+    {
+        var bytes = data.ToArray();
+        var text = Encoding.UTF8.GetString(bytes);
+        
+        if (text.StartsWith("CUSTOM:") && int.TryParse(text.Substring(7), out var value))
+        {
+            return value;
+        }
+        
+        // Fallback to direct parsing if format is unexpected
+        return int.TryParse(text, out var fallbackValue) ? fallbackValue : 0;
+    }
+}

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

@@ -8,6 +8,7 @@
 using Components.TestServer.RazorComponents;
 using Components.TestServer.RazorComponents.Pages.Forms;
 using Components.TestServer.Services;
+using Microsoft.AspNetCore.Components;
 using Microsoft.AspNetCore.Components.Server.Circuits;
 using Microsoft.AspNetCore.Components.Web;
 using Microsoft.AspNetCore.Components.WebAssembly.Server;
@@ -64,6 +65,9 @@ public void ConfigureServices(IServiceCollection services)
         services.AddScoped<InteractiveServerService>();
         services.AddScoped<InteractiveAutoService>();
 
+        // Register custom serializer for E2E testing of persistent component state serialization extensibility
+        services.AddSingleton<IPersistentComponentStateSerializer<int>, CustomIntSerializer>();
+
         services.AddHttpContextAccessor();
         services.AddSingleton<AsyncOperationService>();
         services.AddCascadingAuthenticationState();

src/Components/test/testassets/TestContentPackage/DeclarativePersistStateComponent.razor

@@ -1,4 +1,5 @@
 <p>Application state is <span id="@KeyName">@Value</span></p>
+<p>Custom value is <span id="custom-@KeyName">@CustomValue</span></p>
 <p>Render mode: <span id="render-mode-@KeyName">@_renderMode</span></p>
 
 @code {
@@ -11,11 +12,18 @@
     [PersistentState]
     public string Value { get; set; }
 
+    [PersistentState]
+    public int CustomValue { get; set; }
+
     private string _renderMode = "SSR";
 
     protected override void OnInitialized()
     {
         Value ??= !RendererInfo.IsInteractive ? InitialValue : "not restored";
+        if (CustomValue == 0)
+        {
+            CustomValue = !RendererInfo.IsInteractive ? 42 : 0;
+        }
         _renderMode = OperatingSystem.IsBrowser() ? "WebAssembly" : "Server";
     }
 }