Merge remote-tracking branch 'origin/blazor-wasm-preview4' into blazor-wasm

src/Components/Shared/test/TestWebAssemblyJSRuntimeInvoker.cs

@@ -0,0 +1,37 @@
+// 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 Microsoft.AspNetCore.Components.WebAssembly.Services;
+
+namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
+{
+    internal class TestWebAssemblyJSRuntimeInvoker : WebAssemblyJSRuntimeInvoker
+    {
+        private readonly string _environment;
+
+        public TestWebAssemblyJSRuntimeInvoker(string environment = "Production")
+        {
+            _environment = environment;
+        }
+
+        public override TResult InvokeUnmarshalled<T0, T1, T2, TResult>(string identifier, T0 arg0, T1 arg1, T2 arg2)
+        {
+            switch (identifier)
+            {
+                case "Blazor._internal.getApplicationEnvironment":
+                    return (TResult)(object)_environment;
+                case "Blazor._internal.getConfig":
+                    return (TResult)(object)null;
+                case "Blazor._internal.navigationManager.getBaseURI":
+                    var testUri = "https://www.example.com/awesome-part-that-will-be-truncated-in-tests";
+                    return (TResult)(object)testUri;
+                case "Blazor._internal.navigationManager.getLocationHref":
+                    var testHref = "https://www.example.com/awesome-part-that-will-be-truncated-in-tests/cool";
+                    return (TResult)(object)testHref;
+                default:
+                    throw new NotImplementedException($"{nameof(TestWebAssemblyJSRuntimeInvoker)} has no implementation for '{identifier}'.");
+            }
+        }
+    }
+}

src/Components/Web.JS/src/Platform/Mono/MonoPlatform.ts

@@ -170,16 +170,21 @@ function createEmscriptenModuleInstance(resourceLoader: WebAssemblyResourceLoade
   module.postRun = [];
   (module as any).preloadPlugins = [];
 
+  // Begin loading the .dll/.pdb/.wasm files, but don't block here. Let other loading processes run in parallel.
+  const dotnetWasmResourceName = 'dotnet.wasm';
+  const assembliesBeingLoaded = resourceLoader.loadResources(resources.assembly, filename => `_framework/_bin/${filename}`);
+  const pdbsBeingLoaded = resourceLoader.loadResources(resources.pdb || {}, filename => `_framework/_bin/${filename}`);
+  const wasmBeingLoaded = resourceLoader.loadResource(
+    /* name */ dotnetWasmResourceName,
+    /* url */  `_framework/wasm/${dotnetWasmResourceName}`,
+    /* hash */ resourceLoader.bootConfig.resources.runtime[dotnetWasmResourceName]);
+
   // Override the mechanism for fetching the main wasm file so we can connect it to our cache
   module.instantiateWasm = (imports, successCallback): WebAssembly.Exports => {
     (async () => {
       let compiledInstance: WebAssembly.Instance;
       try {
-        const dotnetWasmResourceName = 'dotnet.wasm';
+        const dotnetWasmResource = await wasmBeingLoaded;
-        const dotnetWasmResource = await resourceLoader.loadResource(
-          /* name */ dotnetWasmResourceName,
-          /* url */  `_framework/wasm/${dotnetWasmResourceName}`,
-          /* hash */ resourceLoader.bootConfig.resources.runtime[dotnetWasmResourceName]);
         compiledInstance = await compileWasmModule(dotnetWasmResource, imports);
       } catch (ex) {
         module.printErr(ex);
@@ -200,12 +205,8 @@ function createEmscriptenModuleInstance(resourceLoader: WebAssemblyResourceLoade
     // Fetch the assemblies and PDBs in the background, telling Mono to wait until they are loaded
     // Mono requires the assembly filenames to have a '.dll' extension, so supply such names regardless
     // of the extensions in the URLs. This allows loading assemblies with arbitrary filenames.
-    resourceLoader.loadResources(resources.assembly, filename => `_framework/_bin/${filename}`)
+    assembliesBeingLoaded.forEach(r => addResourceAsAssembly(r, changeExtension(r.name, '.dll')));
-      .forEach(r => addResourceAsAssembly(r, changeExtension(r.name, '.dll')));
+    pdbsBeingLoaded.forEach(r => addResourceAsAssembly(r, r.name));
-    if (resources.pdb) {
-      resourceLoader.loadResources(resources.pdb, filename => `_framework/_bin/${filename}`)
-        .forEach(r => addResourceAsAssembly(r, r.name));
-    }
   });
 
   module.postRun.push(() => {

src/Components/Web.JS/src/Services/NavigationManager.ts

@@ -13,8 +13,8 @@ export const internalFunctions = {
   listenForNavigationEvents,
   enableNavigationInterception,
   navigateTo,
-  getBaseURI: () => document.baseURI,
+  getBaseURI: () => BINDING.js_string_to_mono_string(document.baseURI),
-  getLocationHref: () => location.href,
+  getLocationHref: () => BINDING.js_string_to_mono_string(location.href),
 };
 
 function listenForNavigationEvents(callback: (uri: string, intercepted: boolean) => Promise<void>) {
@@ -141,4 +141,4 @@ function toBaseUriWithTrailingSlash(baseUri: string) {
 
 function eventHasSpecialKey(event: MouseEvent) {
   return event.ctrlKey || event.shiftKey || event.altKey || event.metaKey;
-}
+}

src/Components/WebAssembly/DebugProxy/src/Hosting/DebugProxyHost.cs

@@ -0,0 +1,63 @@
+// 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.Collections.Generic;
+using System.Text;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+
+namespace Microsoft.AspNetCore.Components.WebAssembly.DebugProxy.Hosting
+{
+    public static class DebugProxyHost
+    {
+        /// <summary>
+        /// Creates a custom HostBuilder for the DebugProxyLauncher so that we can inject
+        /// only the needed configurations.
+        /// </summary>
+        /// <param name="args">Command line arguments passed in</param>
+        /// <param name="browserHost">Host where browser is listening for debug connections</param>
+        /// <returns><see cref="IHostBuilder"></returns>
+        public static IHostBuilder CreateDefaultBuilder(string[] args, string browserHost)
+        {
+            var builder = new HostBuilder();
+
+            builder.ConfigureAppConfiguration((hostingContext, config) =>
+            {
+                if (args != null)
+                {
+                    config.AddCommandLine(args);
+                }
+                config.AddJsonFile("blazor-debugproxysettings.json", optional: true, reloadOnChange: true);
+            })
+            .ConfigureLogging((hostingContext, logging) =>
+            {
+                logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
+                logging.AddConsole();
+                logging.AddDebug();
+                logging.AddEventSourceLogger();
+            })
+            .ConfigureWebHostDefaults(webBuilder =>
+            {
+                webBuilder.UseStartup<Startup>();
+
+                // By default we bind to a dyamic port
+                // This can be overridden using an option like "--urls http://localhost:9500"
+                webBuilder.UseUrls("http://127.0.0.1:0");
+            })
+            .ConfigureServices(serviceCollection =>
+            {
+                serviceCollection.AddSingleton(new DebugProxyOptions
+                {
+                    BrowserHost = browserHost
+                });
+            });
+
+            return builder;
+
+        }
+    }
+}

src/Components/WebAssembly/DebugProxy/src/Program.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Diagnostics;
+using Microsoft.AspNetCore.Components.WebAssembly.DebugProxy.Hosting;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.Extensions.CommandLineUtils;
 using Microsoft.Extensions.Configuration;
@@ -36,29 +37,8 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.DebugProxy
 
             app.OnExecute(() =>
             {
-                var host = Host.CreateDefaultBuilder(args)
+                var browserHost = browserHostOption.HasValue() ? browserHostOption.Value(): "http://127.0.0.1:9222";
-                    .ConfigureAppConfiguration((hostingContext, config) =>
+                var host = DebugProxyHost.CreateDefaultBuilder(args, browserHost).Build();
-                    {
-                        config.AddCommandLine(args);
-                    })
-                    .ConfigureWebHostDefaults(webBuilder =>
-                    {
-                        webBuilder.UseStartup<Startup>();
-
-                        // By default we bind to a dyamic port
-                        // This can be overridden using an option like "--urls http://localhost:9500"
-                        webBuilder.UseUrls("http://127.0.0.1:0");
-                    })
-                    .ConfigureServices(serviceCollection =>
-                    {
-                        serviceCollection.AddSingleton(new DebugProxyOptions
-                        {
-                            BrowserHost = browserHostOption.HasValue()
-                                ? browserHostOption.Value()
-                                : "http://127.0.0.1:9222",
-                        });
-                    })
-                    .Build();
 
                 if (ownerPidOption.HasValue())
                 {

src/Components/WebAssembly/JSInterop/src/WebAssemblyJSRuntime.cs

@@ -42,6 +42,39 @@ namespace Microsoft.JSInterop.WebAssembly
             BeginInvokeJS(0, "DotNet.jsCallDispatcher.endInvokeDotNetFromJS", args);
         }
 
+        /// <summary>
+        /// Invokes the JavaScript function registered with the specified identifier.
+        /// </summary>
+        /// <typeparam name="TResult">The .NET type corresponding to the function's return value type.</typeparam>
+        /// <param name="identifier">The identifier used when registering the target function.</param>
+        /// <returns>The result of the function invocation.</returns>
+        public TResult InvokeUnmarshalled<TResult>(string identifier)
+            => InvokeUnmarshalled<object, object, object, TResult>(identifier, null, null, null);
+
+        /// <summary>
+        /// Invokes the JavaScript function registered with the specified identifier.
+        /// </summary>
+        /// <typeparam name="T0">The type of the first argument.</typeparam>
+        /// <typeparam name="TResult">The .NET type corresponding to the function's return value type.</typeparam>
+        /// <param name="identifier">The identifier used when registering the target function.</param>
+        /// <param name="arg0">The first argument.</param>
+        /// <returns>The result of the function invocation.</returns>
+        public TResult InvokeUnmarshalled<T0, TResult>(string identifier, T0 arg0)
+            => InvokeUnmarshalled<T0, object, object, TResult>(identifier, arg0, null, null);
+
+        /// <summary>
+        /// Invokes the JavaScript function registered with the specified identifier.
+        /// </summary>
+        /// <typeparam name="T0">The type of the first argument.</typeparam>
+        /// <typeparam name="T1">The type of the second argument.</typeparam>
+        /// <typeparam name="TResult">The .NET type corresponding to the function's return value type.</typeparam>
+        /// <param name="identifier">The identifier used when registering the target function.</param>
+        /// <param name="arg0">The first argument.</param>
+        /// <param name="arg1">The second argument.</param>
+        /// <returns>The result of the function invocation.</returns>
+        public TResult InvokeUnmarshalled<T0, T1, TResult>(string identifier, T0 arg0, T1 arg1)
+            => InvokeUnmarshalled<T0, T1, object, TResult>(identifier, arg0, arg1, null);
+
         /// <summary>
         /// Invokes the JavaScript function registered with the specified identifier.
         /// </summary>
@@ -54,7 +87,7 @@ namespace Microsoft.JSInterop.WebAssembly
         /// <param name="arg1">The second argument.</param>
         /// <param name="arg2">The third argument.</param>
         /// <returns>The result of the function invocation.</returns>
-        public virtual TResult InvokeUnmarshalled<T0, T1, T2, TResult>(string identifier, T0 arg0, T1 arg1, T2 arg2)
+        public TResult InvokeUnmarshalled<T0, T1, T2, TResult>(string identifier, T0 arg0, T1 arg1, T2 arg2)
         {
             var result = InternalCalls.InvokeJSUnmarshalled<T0, T1, T2, TResult>(out var exception, identifier, arg0, arg1, arg2);
             return exception != null

src/Components/WebAssembly/JSInterop/src/WebAssemblyJSRuntimeExtensions.cs

@@ -1,70 +0,0 @@
-// 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;
-
-namespace Microsoft.JSInterop.WebAssembly
-{
-    /// <summary>
-    /// Extension methods for <see cref="WebAssemblyJSRuntime"/>.
-    /// </summary>
-    public static class WebAssemblyJSRuntimeExtensions
-    {
-        /// <summary>
-        /// Invokes the JavaScript function registered with the specified identifier.
-        /// </summary>
-        /// <typeparam name="TResult">The .NET type corresponding to the function's return value type.</typeparam>
-        /// <param name="jsRuntime">The <see cref="WebAssemblyJSRuntime"/>.</param>
-        /// <param name="identifier">The identifier used when registering the target function.</param>
-        /// <returns>The result of the function invocation.</returns>
-        public static TResult InvokeUnmarshalled<TResult>(this WebAssemblyJSRuntime jsRuntime, string identifier)
-        {
-            if (jsRuntime is null)
-            {
-                throw new ArgumentNullException(nameof(jsRuntime));
-            }
-
-            return jsRuntime.InvokeUnmarshalled<object, object, object, TResult>(identifier, null, null, null);
-        }
-
-        /// <summary>
-        /// Invokes the JavaScript function registered with the specified identifier.
-        /// </summary>
-        /// <typeparam name="T0">The type of the first argument.</typeparam>
-        /// <typeparam name="TResult">The .NET type corresponding to the function's return value type.</typeparam>
-        /// <param name="jsRuntime">The <see cref="WebAssemblyJSRuntime"/>.</param>
-        /// <param name="identifier">The identifier used when registering the target function.</param>
-        /// <param name="arg0">The first argument.</param>
-        /// <returns>The result of the function invocation.</returns>
-        public static TResult InvokeUnmarshalled<T0, TResult>(this WebAssemblyJSRuntime jsRuntime, string identifier, T0 arg0)
-        {
-            if (jsRuntime is null)
-            {
-                throw new ArgumentNullException(nameof(jsRuntime));
-            }
-
-            return jsRuntime.InvokeUnmarshalled<T0, object, object, TResult>(identifier, arg0, null, null);
-        }
-
-        /// <summary>
-        /// Invokes the JavaScript function registered with the specified identifier.
-        /// </summary>
-        /// <typeparam name="T0">The type of the first argument.</typeparam>
-        /// <typeparam name="T1">The type of the second argument.</typeparam>
-        /// <typeparam name="TResult">The .NET type corresponding to the function's return value type.</typeparam>
-        /// <param name="jsRuntime">The <see cref="WebAssemblyJSRuntime"/>.</param>
-        /// <param name="identifier">The identifier used when registering the target function.</param>
-        /// <param name="arg0">The first argument.</param>
-        /// <param name="arg1">The second argument.</param>
-        /// <returns>The result of the function invocation.</returns>
-        public static TResult InvokeUnmarshalled<T0, T1, TResult>(this WebAssemblyJSRuntime jsRuntime, string identifier, T0 arg0, T1 arg1)
-        {
-            if (jsRuntime is null)
-            {
-                throw new ArgumentNullException(nameof(jsRuntime));
-            }
-
-            return jsRuntime.InvokeUnmarshalled<T0, T1, object, TResult>(identifier, arg0, arg1, null);
-        }
-    }
-}

src/Components/WebAssembly/Server/src/DebugProxyLauncher.cs

@@ -52,7 +52,6 @@ namespace Microsoft.AspNetCore.Builder
                 UseShellExecute = false,
                 RedirectStandardOutput = true,
             };
-            RemoveUnwantedEnvironmentVariables(processStartInfo.Environment);
 
             var debugProxyProcess = Process.Start(processStartInfo);
             CompleteTaskWhenServerIsReady(debugProxyProcess, tcs);
@@ -65,20 +64,6 @@ namespace Microsoft.AspNetCore.Builder
             return await tcs.Task;
         }
 
-        private static void RemoveUnwantedEnvironmentVariables(IDictionary<string, string> environment)
-        {
-            // Generally we expect to pass through most environment variables, since dotnet might
-            // need them for arbitrary reasons to function correctly. However, we specifically don't
-            // want to pass through any ASP.NET Core hosting related ones, since the child process
-            // shouldn't be trying to use the same port numbers, etc. In particular we need to break
-            // the association with IISExpress and the MS-ASPNETCORE-TOKEN check.
-            var keysToRemove = environment.Keys.Where(key => key.StartsWith("ASPNETCORE_")).ToList();
-            foreach (var key in keysToRemove)
-            {
-                environment.Remove(key);
-            }
-        }
-
         private static string LocateDebugProxyExecutable(IWebHostEnvironment environment)
         {
             var assembly = Assembly.Load(environment.ApplicationName);

src/Components/WebAssembly/WebAssembly.Authentication/test/Microsoft.AspNetCore.Components.WebAssembly.Authentication.Tests.csproj

@@ -11,4 +11,8 @@
     <Reference Include="Microsoft.CodeAnalysis.CSharp" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Compile Include="$(ComponentsSharedSourceRoot)\test\TestWebAssemblyJSRuntimeInvoker.cs" Link="Shared\TestWebAssemblyJSRuntimeInvoker.cs" />
+  </ItemGroup>
+
 </Project>

src/Components/WebAssembly/WebAssembly.Authentication/test/WebAssemblyAuthenticationServiceCollectionExtensionsTests.cs

@@ -3,6 +3,7 @@
 
 using System;
 using Microsoft.AspNetCore.Components.WebAssembly.Hosting;
+using Microsoft.AspNetCore.Components.WebAssembly.Services;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Options;
@@ -17,7 +18,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Authentication
         [Fact]
         public void CanResolve_AccessTokenProvider()
         {
-            var builder = new WebAssemblyHostBuilder(GetJSRuntime());
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker());
             builder.Services.AddApiAuthorization();
             var host = builder.Build();
 
@@ -27,7 +28,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Authentication
         [Fact]
         public void CanResolve_IRemoteAuthenticationService()
         {
-            var builder = new WebAssemblyHostBuilder(GetJSRuntime());
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker());
             builder.Services.AddApiAuthorization();
             var host = builder.Build();
 
@@ -37,7 +38,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Authentication
         [Fact]
         public void ApiAuthorizationOptions_ConfigurationDefaultsGetApplied()
         {
-            var builder = new WebAssemblyHostBuilder(GetJSRuntime());
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker());
             builder.Services.AddApiAuthorization();
             var host = builder.Build();
 
@@ -71,7 +72,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Authentication
         [Fact]
         public void ApiAuthorizationOptions_DefaultsCanBeOverriden()
         {
-            var builder = new WebAssemblyHostBuilder(GetJSRuntime());
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker());
             builder.Services.AddApiAuthorization(options =>
             {
                 options.AuthenticationPaths = new RemoteAuthenticationApplicationPathsOptions
@@ -131,7 +132,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Authentication
         [Fact]
         public void OidcOptions_ConfigurationDefaultsGetApplied()
         {
-            var builder = new WebAssemblyHostBuilder(GetJSRuntime());
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker());
             builder.Services.Replace(ServiceDescriptor.Singleton<NavigationManager, TestNavigationManager>());
             builder.Services.AddOidcAuthentication(options => { });
             var host = builder.Build();
@@ -169,7 +170,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Authentication
         [Fact]
         public void OidcOptions_DefaultsCanBeOverriden()
         {
-            var builder = new WebAssemblyHostBuilder(GetJSRuntime());
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker());
             builder.Services.AddOidcAuthentication(options =>
             {
                 options.AuthenticationPaths = new RemoteAuthenticationApplicationPathsOptions
@@ -244,19 +245,5 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Authentication
 
             protected override void NavigateToCore(string uri, bool forceLoad) => throw new System.NotImplementedException();
         }
-
-        private WebAssemblyJSRuntime GetJSRuntime(string environment = "Production")
-        {
-            var jsRuntime = new Mock<WebAssemblyJSRuntime>();
-            jsRuntime.Setup(j => j.InvokeUnmarshalled<object, object, object, string>("Blazor._internal.getApplicationEnvironment", null, null, null))
-                .Returns(environment)
-                .Verifiable();
-
-            jsRuntime.Setup(j => j.InvokeUnmarshalled<string, object, object, byte[]>("Blazor._internal.getConfig", It.IsAny<string>(), null, null))
-                .Returns((byte[])null)
-                .Verifiable();
-
-            return jsRuntime.Object;
-        }
     }
 }

src/Components/WebAssembly/WebAssembly/src/Hosting/IWebAssemblyHostEnvironment.cs

@@ -13,5 +13,10 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
         /// Configured to "Production" when not specified by the host.
         /// </summary>
         string Environment { get; }
+
+        /// <summary>
+        /// Gets the base address for the application. This is typically derived from the "<base href>" value in the host page.
+        /// </summary>
+        string BaseAddress { get; }
     }
 }

src/Components/WebAssembly/WebAssembly/src/Hosting/WebAssemblyHostBuilder.cs

@@ -7,13 +7,13 @@ using System.IO;
 using System.Linq;
 using Microsoft.AspNetCore.Components.Routing;
 using Microsoft.AspNetCore.Components.WebAssembly.Services;
+using Microsoft.AspNetCore.Components.Web;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Configuration.Json;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Logging;
 using Microsoft.JSInterop;
-using Microsoft.JSInterop.WebAssembly;
 
 namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
 {
@@ -35,7 +35,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
             // We don't use the args for anything right now, but we want to accept them
             // here so that it shows up this way in the project templates.
             args ??= Array.Empty<string>();
-            var builder = new WebAssemblyHostBuilder(DefaultWebAssemblyJSRuntime.Instance);
+            var builder = new WebAssemblyHostBuilder(WebAssemblyJSRuntimeInvoker.Instance);
 
             // Right now we don't have conventions or behaviors that are specific to this method
             // however, making this the default for the template allows us to add things like that
@@ -47,7 +47,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
         /// <summary>
         /// Creates an instance of <see cref="WebAssemblyHostBuilder"/> with the minimal configuration.
         /// </summary>
-        internal WebAssemblyHostBuilder(WebAssemblyJSRuntime jsRuntime)
+        internal WebAssemblyHostBuilder(WebAssemblyJSRuntimeInvoker jsRuntimeInvoker)
         {
             // Private right now because we don't have much reason to expose it. This can be exposed
             // in the future if we want to give people a choice between CreateDefault and something
@@ -56,20 +56,32 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
             RootComponents = new RootComponentMappingCollection();
             Services = new ServiceCollection();
 
+            // Retrieve required attributes from JSRuntimeInvoker
+            InitializeNavigationManager(jsRuntimeInvoker);
             InitializeDefaultServices();
 
-            var hostEnvironment = InitializeEnvironment(jsRuntime);
+            var hostEnvironment = InitializeEnvironment(jsRuntimeInvoker);
+            HostEnvironment = hostEnvironment;
 
             _createServiceProvider = () =>
             {
-                return Services.BuildServiceProvider(validateScopes: hostEnvironment.Environment == "Development");
+                return Services.BuildServiceProvider(validateScopes: WebAssemblyHostEnvironmentExtensions.IsDevelopment(hostEnvironment));
             };
         }
 
-        private WebAssemblyHostEnvironment InitializeEnvironment(WebAssemblyJSRuntime jsRuntime)
+        private void InitializeNavigationManager(WebAssemblyJSRuntimeInvoker jsRuntimeInvoker)
         {
-            var applicationEnvironment = jsRuntime.InvokeUnmarshalled<string>("Blazor._internal.getApplicationEnvironment");
+            var baseUri = jsRuntimeInvoker.InvokeUnmarshalled<object, object, object, string>(BrowserNavigationManagerInterop.GetBaseUri, null, null, null);
-            var hostEnvironment = new WebAssemblyHostEnvironment(applicationEnvironment);
+            var uri = jsRuntimeInvoker.InvokeUnmarshalled<object, object, object, string>(BrowserNavigationManagerInterop.GetLocationHref, null, null, null);
+
+            WebAssemblyNavigationManager.Instance = new WebAssemblyNavigationManager(baseUri, uri);
+        }
+
+        private WebAssemblyHostEnvironment InitializeEnvironment(WebAssemblyJSRuntimeInvoker jsRuntimeInvoker)
+        {
+            var applicationEnvironment = jsRuntimeInvoker.InvokeUnmarshalled<object, object, object, string>(
+                "Blazor._internal.getApplicationEnvironment", null, null, null);
+            var hostEnvironment = new WebAssemblyHostEnvironment(applicationEnvironment, WebAssemblyNavigationManager.Instance.BaseUri);
 
             Services.AddSingleton<IWebAssemblyHostEnvironment>(hostEnvironment);
 
@@ -81,9 +93,8 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
 
             foreach (var configFile in configFiles)
             {
-                var appSettingsJson = jsRuntime.InvokeUnmarshalled<string, byte[]>(
+                var appSettingsJson = jsRuntimeInvoker.InvokeUnmarshalled<string, object, object, byte[]>(
-                    "Blazor._internal.getConfig",
+                    "Blazor._internal.getConfig", configFile, null, null);
-                    configFile);
 
                 if (appSettingsJson != null)
                 {
@@ -112,6 +123,11 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
         /// </summary>
         public IServiceCollection Services { get; }
 
+        /// <summary>
+        /// Gets information about the app's host environment.
+        /// </summary>
+        public IWebAssemblyHostEnvironment HostEnvironment { get; }
+
         /// <summary>
         /// Registers a <see cref="IServiceProviderFactory{TBuilder}" /> instance to be used to create the <see cref="IServiceProvider" />.
         /// </summary>
@@ -124,11 +140,11 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
         /// <remarks>
         /// <para>
         /// <see cref="ConfigureContainer{TBuilder}(IServiceProviderFactory{TBuilder}, Action{TBuilder})"/> is called by <see cref="Build"/>
-        /// and so the delegate provided by <paramref name="configure"/> will run after all other services have been registered. 
+        /// and so the delegate provided by <paramref name="configure"/> will run after all other services have been registered.
         /// </para>
         /// <para>
         /// Multiple calls to <see cref="ConfigureContainer{TBuilder}(IServiceProviderFactory{TBuilder}, Action{TBuilder})"/> will replace
-        /// the previously stored <paramref name="factory"/> and <paramref name="configure"/> delegate. 
+        /// the previously stored <paramref name="factory"/> and <paramref name="configure"/> delegate.
         /// </para>
         /// </remarks>
         public void ConfigureContainer<TBuilder>(IServiceProviderFactory<TBuilder> factory, Action<TBuilder> configure = null)

src/Components/WebAssembly/WebAssembly/src/Hosting/WebAssemblyHostEnvironment.cs

@@ -5,8 +5,14 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
 {
     internal sealed class WebAssemblyHostEnvironment : IWebAssemblyHostEnvironment
     {
-        public WebAssemblyHostEnvironment(string environment) => Environment = environment;
+        public WebAssemblyHostEnvironment(string environment, string baseAddress)
+        {
+            Environment = environment;
+            BaseAddress = baseAddress;
+        }
 
         public string Environment { get; }
+
+        public string BaseAddress { get; }
     }
 }

src/Components/WebAssembly/WebAssembly/src/Hosting/WebAssemblyHostEnvironmentExtensions.cs

@@ -0,0 +1,75 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
+{
+    public static class WebAssemblyHostEnvironmentExtensions
+    {
+        /// <summary>
+        /// Checks if the current hosting environment name is <see cref="EnvironmentName.Development"/>.
+        /// </summary>
+        /// <param name="hostingEnvironment">An instance of <see cref="IWebAssemblyHostEnvironment"/>.</param>
+        /// <returns>True if the environment name is <see cref="EnvironmentName.Development"/>, otherwise false.</returns>
+        public static bool IsDevelopment(this IWebAssemblyHostEnvironment hostingEnvironment)
+        {
+            if (hostingEnvironment == null)
+            {
+                throw new ArgumentNullException(nameof(hostingEnvironment));
+            }
+
+            return hostingEnvironment.IsEnvironment("Development");
+        }
+
+        /// <summary>
+        /// Checks if the current hosting environment name is <see cref="EnvironmentName.Staging"/>.
+        /// </summary>
+        /// <param name="hostingEnvironment">An instance of <see cref="IWebAssemblyHostEnvironment"/>.</param>
+        /// <returns>True if the environment name is <see cref="EnvironmentName.Staging"/>, otherwise false.</returns>
+        public static bool IsStaging(this IWebAssemblyHostEnvironment hostingEnvironment)
+        {
+            if (hostingEnvironment == null)
+            {
+                throw new ArgumentNullException(nameof(hostingEnvironment));
+            }
+
+            return hostingEnvironment.IsEnvironment("Staging");
+        }
+
+        /// <summary>
+        /// Checks if the current hosting environment name is <see cref="EnvironmentName.Production"/>.
+        /// </summary>
+        /// <param name="hostingEnvironment">An instance of <see cref="IWebAssemblyHostEnvironment"/>.</param>
+        /// <returns>True if the environment name is <see cref="EnvironmentName.Production"/>, otherwise false.</returns>
+        public static bool IsProduction(this IWebAssemblyHostEnvironment hostingEnvironment)
+        {
+            if (hostingEnvironment == null)
+            {
+                throw new ArgumentNullException(nameof(hostingEnvironment));
+            }
+
+            return hostingEnvironment.IsEnvironment("Production");
+        }
+
+        /// <summary>
+        /// Compares the current hosting environment name against the specified value.
+        /// </summary>
+        /// <param name="hostingEnvironment">An instance of <see cref="IWebAssemblyHostEnvironment"/>.</param>
+        /// <param name="environmentName">Environment name to validate against.</param>
+        /// <returns>True if the specified name is the same as the current environment, otherwise false.</returns>
+        public static bool IsEnvironment(
+            this IWebAssemblyHostEnvironment hostingEnvironment,
+            string environmentName)
+        {
+            if (hostingEnvironment == null)
+            {
+                throw new ArgumentNullException(nameof(hostingEnvironment));
+            }
+
+            return string.Equals(
+                hostingEnvironment.Environment,
+                environmentName,
+                StringComparison.OrdinalIgnoreCase);
+        }
+    }
+}

src/Components/WebAssembly/WebAssembly/src/Services/HttpClientServiceCollectionExtensions.cs

@@ -1,31 +0,0 @@
-// 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.Net.Http;
-using Microsoft.AspNetCore.Components;
-
-namespace Microsoft.Extensions.DependencyInjection
-{
-    public static class HttpClientServiceCollectionExtensions
-    {
-        /// <summary>
-        /// Adds a <see cref="HttpClient" /> instance to the <paramref name="serviceCollection" /> that is
-        /// configured to use the application's base address (<seealso cref="NavigationManager.BaseUri" />).
-        /// </summary>
-        /// <param name="serviceCollection">The <see cref="IServiceCollection" />.</param>
-        /// <returns>The configured <see cref="IServiceCollection" />.</returns>
-        public static IServiceCollection AddBaseAddressHttpClient(this IServiceCollection serviceCollection)
-        {
-             return serviceCollection.AddSingleton(s =>
-            {
-                // Creating the URI helper needs to wait until the JS Runtime is initialized, so defer it.
-                var navigationManager = s.GetRequiredService<NavigationManager>();
-                return new HttpClient
-                {
-                    BaseAddress = new Uri(navigationManager.BaseUri)
-                };
-            });
-        }
-    }
-}

src/Components/WebAssembly/WebAssembly/src/Services/WebAssemblyJSRuntimeInvoker.cs

@@ -0,0 +1,27 @@
+// 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 Microsoft.JSInterop.WebAssembly;
+
+namespace Microsoft.AspNetCore.Components.WebAssembly.Services
+{
+    /// <summary>
+    /// This class exists to enable unit testing for code that needs to call
+    /// <see cref="WebAssemblyJSRuntime.InvokeUnmarshalled{T0, T1, T2, TResult}(string, T0, T1, T2)"/>.
+    ///
+    /// We should only use this in non-perf-critical code paths (for example, during hosting startup,
+    /// where we only call this a fixed number of times, and not during rendering where it might be
+    /// called arbitrarily frequently due to application logic). In perf-critical code paths, use
+    /// <see cref="DefaultWebAssemblyJSRuntime.Instance"/> and call it directly.
+    ///
+    /// It might not ultimately make any difference but we won't know until we integrate AoT support.
+    /// When AoT is used, it's possible that virtual dispatch will force fallback on the interpreter.
+    /// </summary>
+    internal class WebAssemblyJSRuntimeInvoker
+    {
+        public static WebAssemblyJSRuntimeInvoker Instance = new WebAssemblyJSRuntimeInvoker();
+
+        public virtual TResult InvokeUnmarshalled<T0, T1, T2, TResult>(string identifier, T0 arg0, T1 arg1, T2 arg2)
+            => DefaultWebAssemblyJSRuntime.Instance.InvokeUnmarshalled<T0, T1, T2, TResult>(identifier, arg0, arg1, arg2);
+    }
+}

src/Components/WebAssembly/WebAssembly/src/Services/WebAssemblyNavigationManager.cs

@@ -15,21 +15,10 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Services
         /// <summary>
         /// Gets the instance of <see cref="WebAssemblyNavigationManager"/>.
         /// </summary>
-        public static readonly WebAssemblyNavigationManager Instance = new WebAssemblyNavigationManager();
+        public static WebAssemblyNavigationManager Instance { get; set; }
 
-        // For simplicity we force public consumption of the BrowserNavigationManager through
+        public WebAssemblyNavigationManager(string baseUri, string uri)
-        // a singleton. Only a single instance can be updated by the browser through
-        // interop. We can construct instances for testing.
-        internal WebAssemblyNavigationManager()
         {
-        }
-
-        protected override void EnsureInitialized()
-        {
-            // As described in the comment block above, BrowserNavigationManager is only for
-            // client-side (Mono) use, so it's OK to rely on synchronicity here.
-            var baseUri = DefaultWebAssemblyJSRuntime.Instance.Invoke<string>(Interop.GetBaseUri);
-            var uri = DefaultWebAssemblyJSRuntime.Instance.Invoke<string>(Interop.GetLocationHref);
             Initialize(baseUri, uri);
         }
 

src/Components/WebAssembly/WebAssembly/test/Hosting/TestWebAssemblyJSRuntime.cs

@@ -1,25 +0,0 @@
-// 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 Microsoft.JSInterop.WebAssembly;
-using Moq;
-
-namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
-{
-    public class TestWebAssemblyJSRuntime
-    {
-        public static WebAssemblyJSRuntime Create(string environment = "Production")
-        {
-            var jsRuntime = new Mock<WebAssemblyJSRuntime>();
-            jsRuntime.Setup(j => j.InvokeUnmarshalled<object, object, object, string>("Blazor._internal.getApplicationEnvironment", null, null, null))
-                .Returns(environment)
-                .Verifiable();
-
-            jsRuntime.Setup(j => j.InvokeUnmarshalled<string, object, object, byte[]>("Blazor._internal.getConfig", It.IsAny<string>(), null, null))
-                .Returns((byte[])null)
-                .Verifiable();
-
-            return jsRuntime.Object;
-        }
-    }
-}

src/Components/WebAssembly/WebAssembly/test/Hosting/WebAssemblyHostBuilderTest.cs

@@ -7,6 +7,7 @@ using System.Text;
 using Microsoft.AspNetCore.Components.Routing;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyModel;
 using Microsoft.Extensions.Logging;
 using Microsoft.JSInterop;
 using Microsoft.JSInterop.WebAssembly;
@@ -21,7 +22,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
         public void Build_AllowsConfiguringConfiguration()
         {
             // Arrange
-            var builder = new WebAssemblyHostBuilder(TestWebAssemblyJSRuntime.Create());
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker());
 
             builder.Configuration.AddInMemoryCollection(new[]
             {
@@ -39,7 +40,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
         public void Build_AllowsConfiguringServices()
         {
             // Arrange
-            var builder = new WebAssemblyHostBuilder(TestWebAssemblyJSRuntime.Create());
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker());
 
             // This test also verifies that we create a scope.
             builder.Services.AddScoped<StringBuilder>();
@@ -55,7 +56,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
         public void Build_AllowsConfiguringContainer()
         {
             // Arrange
-            var builder = new WebAssemblyHostBuilder(TestWebAssemblyJSRuntime.Create());
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker());
 
             builder.Services.AddScoped<StringBuilder>();
             var factory = new MyFakeServiceProviderFactory();
@@ -73,7 +74,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
         public void Build_AllowsConfiguringContainer_WithDelegate()
         {
             // Arrange
-            var builder = new WebAssemblyHostBuilder(TestWebAssemblyJSRuntime.Create());
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker());
 
             builder.Services.AddScoped<StringBuilder>();
 
@@ -96,7 +97,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
         public void Build_InDevelopment_ConfiguresWithServiceProviderWithScopeValidation()
         {
             // Arrange
-            var builder = new WebAssemblyHostBuilder(TestWebAssemblyJSRuntime.Create(environment: "Development"));
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker(environment: "Development"));
 
             builder.Services.AddScoped<StringBuilder>();
             builder.Services.AddSingleton<TestServiceThatTakesStringBuilder>();
@@ -113,7 +114,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
         public void Build_InProduction_ConfiguresWithServiceProviderWithScopeValidation()
         {
             // Arrange
-            var builder = new WebAssemblyHostBuilder(TestWebAssemblyJSRuntime.Create());
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker());
 
             builder.Services.AddScoped<StringBuilder>();
             builder.Services.AddSingleton<TestServiceThatTakesStringBuilder>();
@@ -126,6 +127,33 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
             Assert.NotNull(host.Services.GetRequiredService<TestServiceThatTakesStringBuilder>());
         }
 
+        [Fact]
+        public void Builder_InDevelopment_SetsHostEnvironmentProperty()
+        {
+            // Arrange
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker(environment: "Development"));
+
+            // Assert
+            Assert.NotNull(builder.HostEnvironment);
+            Assert.True(WebAssemblyHostEnvironmentExtensions.IsDevelopment(builder.HostEnvironment));
+        }
+
+        [Fact]
+        public void Builder_CreatesNavigationManager()
+        {
+            // Arrange
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker(environment: "Development"));
+
+            // Act
+            var host = builder.Build();
+
+            // Assert
+            var navigationManager = host.Services.GetRequiredService<NavigationManager>();
+            Assert.NotNull(navigationManager);
+            Assert.Equal("https://www.example.com/", navigationManager.BaseUri);
+            Assert.Equal("https://www.example.com/awesome-part-that-will-be-truncated-in-tests/cool", navigationManager.Uri);
+        }
+
         private class TestServiceThatTakesStringBuilder
         {
             public TestServiceThatTakesStringBuilder(StringBuilder builder) { }
@@ -165,7 +193,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
         public void Build_AddsConfigurationToServices()
         {
             // Arrange
-            var builder = new WebAssemblyHostBuilder(TestWebAssemblyJSRuntime.Create());
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker());
 
             builder.Configuration.AddInMemoryCollection(new[]
             {
@@ -200,7 +228,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
         public void Constructor_AddsDefaultServices()
         {
             // Arrange & Act
-            var builder = new WebAssemblyHostBuilder(TestWebAssemblyJSRuntime.Create());
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker());
 
             // Assert
             Assert.Equal(DefaultServiceTypes.Count, builder.Services.Count);

src/Components/WebAssembly/WebAssembly/test/Hosting/WebAssemblyHostTest.cs

@@ -18,7 +18,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
         public async Task RunAsync_CanExitBasedOnCancellationToken()
         {
             // Arrange
-            var builder = new WebAssemblyHostBuilder(TestWebAssemblyJSRuntime.Create());
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker());
             var host = builder.Build();
 
             var cts = new CancellationTokenSource();
@@ -36,7 +36,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
         public async Task RunAsync_CallingTwiceCausesException()
         {
             // Arrange
-            var builder = new WebAssemblyHostBuilder(TestWebAssemblyJSRuntime.Create());
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker());
             var host = builder.Build();
 
             var cts = new CancellationTokenSource();
@@ -56,7 +56,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Hosting
         public async Task DisposeAsync_CanDisposeAfterCallingRunAsync()
         {
             // Arrange
-            var builder = new WebAssemblyHostBuilder(TestWebAssemblyJSRuntime.Create());
+            var builder = new WebAssemblyHostBuilder(new TestWebAssemblyJSRuntimeInvoker());
             builder.Services.AddSingleton<DisposableService>();
             var host = builder.Build();
 

src/Components/WebAssembly/WebAssembly/test/Microsoft.AspNetCore.Components.WebAssembly.Tests.csproj

@@ -9,4 +9,8 @@
     <Reference Include="Microsoft.CodeAnalysis.CSharp" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Compile Include="$(ComponentsSharedSourceRoot)\test\TestWebAssemblyJSRuntimeInvoker.cs" Link="Shared\TestWebAssemblyJSRuntimeInvoker.cs" />
+  </ItemGroup>
+
 </Project>

src/Components/WebAssembly/testassets/StandaloneApp/Program.cs

@@ -1,6 +1,8 @@
 // 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.Net.Http;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Components.WebAssembly.Hosting;
 using Microsoft.Extensions.DependencyInjection;
@@ -13,7 +15,7 @@ namespace StandaloneApp
         {
             var builder = WebAssemblyHostBuilder.CreateDefault(args);
             builder.RootComponents.Add<App>("app");
-            builder.Services.AddBaseAddressHttpClient();
+            builder.Services.AddSingleton(new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });
 
             await builder.Build().RunAsync();
         }

src/Components/test/E2ETest/Tests/ClientSideHostingTest.cs

@@ -32,7 +32,7 @@ namespace Microsoft.AspNetCore.Components.E2ETest.Tests
         [Fact]
         public void MapFallbackToClientSideBlazor_FilePath()
         {
-            Navigate("/filepath");
+            Navigate("/subdir/filepath");
             WaitUntilLoaded();
             Assert.NotNull(Browser.FindElement(By.Id("test-selector")));
         }
@@ -40,7 +40,7 @@ namespace Microsoft.AspNetCore.Components.E2ETest.Tests
         [Fact]
         public void MapFallbackToClientSideBlazor_Pattern_FilePath()
         {
-            Navigate("/pattern_filepath/test");
+            Navigate("/subdir/pattern_filepath/test");
             WaitUntilLoaded();
             Assert.NotNull(Browser.FindElement(By.Id("test-selector")));
         }
@@ -48,7 +48,7 @@ namespace Microsoft.AspNetCore.Components.E2ETest.Tests
         [Fact]
         public void MapFallbackToClientSideBlazor_AssemblyPath_FilePath()
         {
-            Navigate("/assemblypath_filepath");
+            Navigate("/subdir/assemblypath_filepath");
             WaitUntilLoaded();
             Assert.NotNull(Browser.FindElement(By.Id("test-selector")));
         }
@@ -56,7 +56,7 @@ namespace Microsoft.AspNetCore.Components.E2ETest.Tests
         [Fact]
         public void MapFallbackToClientSideBlazor_AssemblyPath_Pattern_FilePath()
         {
-            Navigate("/assemblypath_pattern_filepath/test");
+            Navigate("/subdir/assemblypath_pattern_filepath/test");
             WaitUntilLoaded();
             Assert.NotNull(Browser.FindElement(By.Id("test-selector")));
         }

src/Components/test/testassets/BasicTestApp/Program.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Globalization;
 using System.Linq;
+using System.Net.Http;
 using System.Runtime.InteropServices;
 using System.Threading.Tasks;
 using BasicTestApp.AuthTest;
@@ -36,7 +37,7 @@ namespace BasicTestApp
 
             builder.RootComponents.Add<Index>("root");
 
-            builder.Services.AddBaseAddressHttpClient();
+            builder.Services.AddSingleton(new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });
             builder.Services.AddSingleton<AuthenticationStateProvider, ServerAuthenticationStateProvider>();
             builder.Services.AddAuthorizationCore(options =>
             {

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

@@ -23,6 +23,7 @@ namespace TestServer
                 ["Server authentication"] = (BuildWebHost<ServerAuthenticationStartup>(CreateAdditionalArgs(args)), "/subdir"),
                 ["CORS (WASM)"] = (BuildWebHost<CorsStartup>(CreateAdditionalArgs(args)), "/subdir"),
                 ["Prerendering (Server-side)"] = (BuildWebHost<PrerenderedStartup>(CreateAdditionalArgs(args)), "/prerendered"),
+                ["Client-side with fallback"] = (BuildWebHost<StartupWithMapFallbackToClientSideBlazor>(CreateAdditionalArgs(args)), "/fallback"),
                 ["Multiple components (Server-side)"] = (BuildWebHost<MultipleComponents>(CreateAdditionalArgs(args)), "/multiple-components"),
                 ["Globalization + Localization (Server-side)"] = (BuildWebHost<InternationalizationStartup>(CreateAdditionalArgs(args)), "/subdir"),
                 ["Server-side blazor"] = (BuildWebHost<ServerStartup>(CreateAdditionalArgs(args)), "/subdir"),

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

@@ -31,50 +31,43 @@ namespace TestServer
             }
 
             // The client-side files middleware needs to be here because the base href in hardcoded to /subdir/
-            app.Map("/subdir", app =>
+            app.Map("/subdir", subApp =>
             {
-                app.UseBlazorFrameworkFiles();
+                subApp.UseBlazorFrameworkFiles();
-                app.UseStaticFiles();
+                subApp.UseStaticFiles();
-            });
 
-            // The calls to `Map` allow us to test each of these overloads, while keeping them isolated.
+                // The calls to `Map` allow us to test each of these overloads, while keeping them isolated.
-            app.Map("/filepath", app =>
+                subApp.Map("/filepath", filepath =>
-            {
-                app.UseRouting();
-
-                app.UseEndpoints(endpoints =>
                 {
-                    endpoints.MapFallbackToFile("index.html");
+                    filepath.UseRouting();
+                    filepath.UseEndpoints(endpoints =>
+                    {
+                        endpoints.MapFallbackToFile("index.html");
+                    });
                 });
-            });
+                subApp.Map("/pattern_filepath", patternFilePath =>
-
-            app.Map("/pattern_filepath", app =>
-            {
-                app.UseRouting();
-
-                app.UseEndpoints(endpoints =>
                 {
-                    endpoints.MapFallbackToFile("test/{*path:nonfile}", "index.html");
+                    patternFilePath.UseRouting();
+                    patternFilePath.UseEndpoints(endpoints =>
+                    {
+                        endpoints.MapFallbackToFile("test/{*path:nonfile}", "index.html");
+                    });
                 });
-            });
+                subApp.Map("/assemblypath_filepath", assemblyPathFilePath =>
-
-            app.Map("/assemblypath_filepath", app =>
-            {
-                app.UseRouting();
-
-                app.UseEndpoints(endpoints =>
                 {
-                    endpoints.MapFallbackToFile("index.html");
+                    assemblyPathFilePath.UseRouting();
+                    assemblyPathFilePath.UseEndpoints(endpoints =>
+                    {
+                        endpoints.MapFallbackToFile("index.html");
+                    });
                 });
-            });
+                subApp.Map("/assemblypath_pattern_filepath", assemblyPatternFilePath =>
-
-            app.Map("/assemblypath_pattern_filepath", app =>
-            {
-                app.UseRouting();
-
-                app.UseEndpoints(endpoints =>
                 {
-                    endpoints.MapFallbackToFile("test/{*path:nonfile}", "index.html");
+                    assemblyPatternFilePath.UseRouting();
+                    assemblyPatternFilePath.UseEndpoints(endpoints =>
+                    {
+                        endpoints.MapFallbackToFile("test/{*path:nonfile}", "index.html");
+                    });
                 });
             });
         }

src/ProjectTemplates/ComponentsWebAssembly.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Client/Program.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Net.Http;
 using System.Collections.Generic;
 using System.Threading.Tasks;
 using System.Text;
@@ -18,7 +19,7 @@ namespace ComponentsWebAssembly_CSharp
             var builder = WebAssemblyHostBuilder.CreateDefault(args);
             builder.RootComponents.Add<App>("app");
 
-            builder.Services.AddBaseAddressHttpClient();
+            builder.Services.AddSingleton(new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });
 #if (IndividualLocalAuth)
     #if (Hosted)
             builder.Services.AddApiAuthorization();