Add E2E tests for webworker template

src/ProjectTemplates/test/Templates.Blazor.Tests/Templates.Blazor.Tests.csproj

@@ -47,6 +47,13 @@
     </Content>
   </ItemGroup>
 
+  <ItemGroup>
+    <Content Include="TestAssets\**\*">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <Compile Remove="TestAssets\**\*.cs" />
+  </ItemGroup>
+
   <ItemGroup>
     <Reference Include="Microsoft.AspNetCore.Routing" />
     <Reference Include="Microsoft.AspNetCore.Routing.Abstractions" />

src/ProjectTemplates/test/Templates.Blazor.Tests/TestAssets/WebWorker/TestWorkerMethods.cs

@@ -0,0 +1,26 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Runtime.InteropServices.JavaScript;
+using System.Runtime.Versioning;
+using System.Text.Json;
+
+namespace TestWorkerExports;
+
+[SupportedOSPlatform("browser")]
+public static partial class TestWorkerMethods
+{
+    [JSExport]
+    public static int Add(int a, int b) => a + b;
+
+    [JSExport]
+    public static string Echo(string input) => input;
+
+    [JSExport]
+    public static string GetPersonJson()
+        => JsonSerializer.Serialize(new { Name = "Alice", Age = 30 });
+
+    [JSExport]
+    public static string ThrowError()
+        => throw new InvalidOperationException("Test exception from worker");
+}

src/ProjectTemplates/test/Templates.Blazor.Tests/TestAssets/WebWorker/WebWorkerTest.razor

@@ -0,0 +1,125 @@
+@* Licensed to the .NET Foundation under one or more agreements. *@
+@* The .NET Foundation licenses this file to you under the MIT license. *@
+
+@page "/webworker-test"
+
+@using WorkerLib
+@inject IJSRuntime JSRuntime
+@implements IAsyncDisposable
+
+<PageTitle>WebWorker Test</PageTitle>
+
+<div id="webworker-test">
+    <h3>WebWorker E2E Test</h3>
+
+    <div>
+        <button id="btn-init" @onclick="InitWorker">Initialize Worker</button>
+        <span id="init-status">@InitStatus</span>
+    </div>
+
+    <div>
+        <button id="btn-add" @onclick="TestAdd" disabled="@(!IsReady)">Test Add</button>
+        <span id="add-result">@AddResult</span>
+    </div>
+
+    <div>
+        <button id="btn-echo" @onclick="TestEcho" disabled="@(!IsReady)">Test Echo</button>
+        <span id="echo-result">@EchoResult</span>
+    </div>
+
+    <div>
+        <button id="btn-error" @onclick="TestError" disabled="@(!IsReady)">Test Error</button>
+        <span id="error-result">@ErrorResult</span>
+    </div>
+
+    <div>
+        <button id="btn-dispose" @onclick="DisposeWorker" disabled="@(!IsReady)">Dispose Worker</button>
+        <span id="dispose-status">@DisposeStatus</span>
+    </div>
+</div>
+
+@code {
+    private WebWorkerClient? Worker;
+    private string InitStatus = "Not initialized";
+    private string AddResult = "";
+    private string EchoResult = "";
+    private string ErrorResult = "";
+    private string DisposeStatus = "";
+
+    private bool IsReady => Worker != null && DisposeStatus != "Disposed";
+
+    private async Task InitWorker()
+    {
+        try
+        {
+            InitStatus = "Initializing...";
+            StateHasChanged();
+            await Task.Yield();
+
+            Worker = await WebWorkerClient.CreateAsync(JSRuntime);
+            InitStatus = "Ready";
+        }
+        catch (Exception ex)
+        {
+            InitStatus = $"Error: {ex.Message}";
+            Console.WriteLine($"[WebWorkerTest] Init error: {ex}");
+        }
+    }
+
+    private async Task TestAdd()
+    {
+        try
+        {
+            var result = await Worker!.InvokeAsync<int>("TestWorkerExports.TestWorkerMethods.Add", [5, 3]);
+            AddResult = result == 8 ? "8" : $"Unexpected: {result}";
+        }
+        catch (Exception ex)
+        {
+            AddResult = $"Error: {ex.Message}";
+        }
+    }
+
+    private async Task TestEcho()
+    {
+        try
+        {
+            var result = await Worker!.InvokeAsync<string>("TestWorkerExports.TestWorkerMethods.Echo", ["Hello Worker"]);
+            EchoResult = result == "Hello Worker" ? "Hello Worker" : $"Unexpected: {result}";
+        }
+        catch (Exception ex)
+        {
+            EchoResult = $"Error: {ex.Message}";
+        }
+    }
+
+    private async Task TestError()
+    {
+        try
+        {
+            await Worker!.InvokeAsync<string>("TestWorkerExports.TestWorkerMethods.ThrowError", []);
+            ErrorResult = "No error thrown";
+        }
+        catch (Exception ex)
+        {
+            ErrorResult = ex.Message.Contains("Test exception") ? "Caught expected error" : $"Wrong error: {ex.Message}";
+        }
+    }
+
+    private async Task DisposeWorker()
+    {
+        if (Worker != null)
+        {
+            await Worker.DisposeAsync();
+            Worker = null;
+            DisposeStatus = "Disposed";
+        }
+    }
+
+    public async ValueTask DisposeAsync()
+    {
+        if (Worker != null)
+        {
+            await Worker.DisposeAsync();
+        }
+    }
+}