Make static prerendering support auth. Fixes #11799 (#12318)

* Make E2E prerendering test use static prerendering (we no longer need coverage for stateful prerendering)

* Use authentication state during static prerendering. This replicates issue #11799 in the E2E test

* Initialize the authentication state provider during static prerendering

* Update ref assembly

* Update unit test

Author: SteveSandersonMS

src/Components/Components/ref/Microsoft.AspNetCore.Components.netstandard2.0.cs

@@ -359,6 +359,10 @@ public partial interface IHandleEvent
     {
         System.Threading.Tasks.Task HandleEventAsync(Microsoft.AspNetCore.Components.EventCallbackWorkItem item, object arg);
     }
+    public partial interface IHostEnvironmentAuthenticationStateProvider
+    {
+        void SetAuthenticationState(System.Threading.Tasks.Task<Microsoft.AspNetCore.Components.AuthenticationState> authenticationStateTask);
+    }
     [System.AttributeUsageAttribute(System.AttributeTargets.Property, AllowMultiple=false, Inherited=true)]
     public sealed partial class InjectAttribute : System.Attribute
     {

src/Components/Components/src/Auth/IHostEnvironmentAuthenticationStateProvider.cs

@@ -0,0 +1,20 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNetCore.Components
+{
+    /// <summary>
+    /// An interface implemented by <see cref="AuthenticationStateProvider"/> classes that can receive authentication
+    /// state information from the host environment.
+    /// </summary>
+    public interface IHostEnvironmentAuthenticationStateProvider
+    {
+        /// <summary>
+        /// Supplies updated authentication state data to the <see cref="AuthenticationStateProvider"/>.
+        /// </summary>
+        /// <param name="authenticationStateTask">A task that resolves with the updated <see cref="AuthenticationState"/>.</param>
+        void SetAuthenticationState(Task<AuthenticationState> authenticationStateTask);
+    }
+}

src/Components/Server/src/Circuits/DefaultCircuitFactory.cs

@@ -14,6 +14,7 @@
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.JSInterop;
+using System.Threading.Tasks;
 
 namespace Microsoft.AspNetCore.Components.Server.Circuits
 {
@@ -50,9 +51,12 @@ public override CircuitHost CreateCircuitHost(
             jsRuntime.Initialize(client);
             componentContext.Initialize(client);
 
-            // You can replace the AuthenticationStateProvider with a custom one, but in that case initialization is up to you
-            var authenticationStateProvider = scope.ServiceProvider.GetService<AuthenticationStateProvider>();
-            (authenticationStateProvider as FixedAuthenticationStateProvider)?.Initialize(httpContext.User);
+            var authenticationStateProvider = scope.ServiceProvider.GetService<AuthenticationStateProvider>() as IHostEnvironmentAuthenticationStateProvider;
+            if (authenticationStateProvider != null)
+            {
+                var authenticationState = new AuthenticationState(httpContext.User); // TODO: Get this from the hub connection context instead
+                authenticationStateProvider.SetAuthenticationState(Task.FromResult(authenticationState));
+            }
 
             var uriHelper = (RemoteUriHelper)scope.ServiceProvider.GetRequiredService<IUriHelper>();
             var navigationInterception = (RemoteNavigationInterception)scope.ServiceProvider.GetRequiredService<INavigationInterception>();

src/Components/Server/src/Circuits/FixedAuthenticationStateProvider.cs

@@ -0,0 +1,26 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNetCore.Components.Server.Circuits
+{
+    /// <summary>
+    /// An <see cref="AuthenticationStateProvider"/> intended for use in server-side Blazor.
+    /// </summary>
+    internal class ServerAuthenticationStateProvider : AuthenticationStateProvider, IHostEnvironmentAuthenticationStateProvider
+    {
+        private Task<AuthenticationState> _authenticationStateTask;
+
+        public override Task<AuthenticationState> GetAuthenticationStateAsync()
+            => _authenticationStateTask
+            ?? throw new InvalidOperationException($"{nameof(GetAuthenticationStateAsync)} was called before {nameof(SetAuthenticationState)}.");
+
+        public void SetAuthenticationState(Task<AuthenticationState> authenticationStateTask)
+        {
+            _authenticationStateTask = authenticationStateTask ?? throw new ArgumentNullException(nameof(authenticationStateTask));
+            NotifyAuthenticationStateChanged(_authenticationStateTask);
+        }
+    }
+}

src/Components/Server/src/Circuits/ServerAuthenticationStateProvider.cs

@@ -76,7 +76,7 @@ public static IServerSideBlazorBuilder AddServerSideBlazor(this IServiceCollecti
             services.AddScoped<IJSRuntime, RemoteJSRuntime>();
             services.AddScoped<INavigationInterception, RemoteNavigationInterception>();
             services.AddScoped<IComponentContext, RemoteComponentContext>();
-            services.AddScoped<AuthenticationStateProvider, FixedAuthenticationStateProvider>();
+            services.AddScoped<AuthenticationStateProvider, ServerAuthenticationStateProvider>();
 
             services.TryAddEnumerable(ServiceDescriptor.Singleton<IConfigureOptions<CircuitOptions>, CircuitOptionsJSInteropDetailedErrorsConfiguration>());
 

src/Components/Server/src/DependencyInjection/ComponentServiceCollectionExtensions.cs

@@ -0,0 +1,49 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Security.Claims;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Components.Server.Circuits;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Components.Server.Tests.Circuits
+{
+    public class ServerAuthenticationStateProviderTest
+    {
+        [Fact]
+        public async Task CannotProvideAuthenticationStateBeforeInitialization()
+        {
+            await Assert.ThrowsAsync<InvalidOperationException>(() =>
+                new ServerAuthenticationStateProvider()
+                    .GetAuthenticationStateAsync());
+        }
+
+        [Fact]
+        public async Task SuppliesAuthenticationStateWithFixedUser()
+        {
+            // Arrange
+            var user = new ClaimsPrincipal();
+            var provider = new ServerAuthenticationStateProvider();
+
+            // Act 1
+            var expectedAuthenticationState1 = new AuthenticationState(user);
+            provider.SetAuthenticationState(Task.FromResult(expectedAuthenticationState1));
+
+            // Assert 1
+            var actualAuthenticationState1 = await provider.GetAuthenticationStateAsync();
+            Assert.NotNull(actualAuthenticationState1);
+            Assert.Same(expectedAuthenticationState1, actualAuthenticationState1);
+
+            // Act 2: Show we can update it further
+            var expectedAuthenticationState2 = new AuthenticationState(user);
+            provider.SetAuthenticationState(Task.FromResult(expectedAuthenticationState2));
+
+            // Assert 2
+            var actualAuthenticationState2 = await provider.GetAuthenticationStateAsync();
+            Assert.NotNull(actualAuthenticationState2);
+            Assert.NotSame(actualAuthenticationState1, actualAuthenticationState2);
+            Assert.Same(expectedAuthenticationState2, actualAuthenticationState2);
+        }
+    }
+}

src/Components/Server/test/Circuits/FixedAuthenticationStateProviderTest.cs

@@ -2,18 +2,20 @@
 @using Microsoft.AspNetCore.Components
 @inject IComponentContext ComponentContext
 
-<h1>Hello</h1>
+<CascadingAuthenticationState>
+    <h1>Hello</h1>
 
-<p>
-    Current state:
-    <strong id="connected-state">@(ComponentContext.IsConnected ? "connected" : "not connected")</strong>
-</p>
+    <p>
+        Current state:
+        <strong id="connected-state">@(ComponentContext.IsConnected ? "connected" : "not connected")</strong>
+    </p>
 
-<p>
-    Clicks:
-    <strong id="count">@count</strong>
-    <button id="increment-count" @onclick="@(() => count++)">Click me</button>
-</p>
+    <p>
+        Clicks:
+        <strong id="count">@count</strong>
+        <button id="increment-count" @onclick="@(() => count++)">Click me</button>
+    </p>
+</CascadingAuthenticationState>
 
 @code {
     int count;

src/Components/Server/test/Circuits/ServerAuthenticationStateProviderTest.cs

@@ -7,7 +7,7 @@
     <base href="~/" />
 </head>
 <body>
-    <app>@(await Html.RenderComponentAsync<TestRouter>())</app>
+    <app>@(await Html.RenderStaticComponentAsync<TestRouter>())</app>
 
     @*
         So that E2E tests can make assertions about both the prerendered and
@@ -19,17 +19,17 @@
 
     <script src="_framework/blazor.server.js" autostart="false"></script>
     <script>
-    // Used by InteropOnInitializationComponent
-    function setElementValue(element, newValue) {
-      element.value = newValue;
-      return element.value;
-            }
+        // Used by InteropOnInitializationComponent
+        function setElementValue(element, newValue) {
+            element.value = newValue;
+            return element.value;
+        }
 
-    function start() {
-        Blazor.start({
-            logLevel: 1 // LogLevel.Debug
-        });
-    }
+        function start() {
+            Blazor.start({
+                logLevel: 1 // LogLevel.Debug
+            });
+        }
     </script>
 </body>
 </html>