[Identity] Move to use static web assets support. (#11029)

* Moves Identity UI to use Static Web Assets
  * Removes the static files as embedded content.
  * Stops plugging the static assets through the embedded file provider.
  * Selects the UI framework at build time instead of runtime.

src/Identity/IdentityNoDeps.slnf

@@ -0,0 +1,24 @@
+{
+  "solution": {
+    "path": "Identity.sln",
+    "projects": [
+      "ApiAuthorization.IdentityServer\\samples\\ApiAuthSample\\ApiAuthSample.csproj",
+      "ApiAuthorization.IdentityServer\\src\\Microsoft.AspNetCore.ApiAuthorization.IdentityServer.csproj",
+      "ApiAuthorization.IdentityServer\\test\\Microsoft.AspNetCore.ApiAuthorization.IdentityServer.Tests.csproj",
+      "Core\\src\\Microsoft.AspNetCore.Identity.csproj",
+      "EntityFrameworkCore\\src\\Microsoft.AspNetCore.Identity.EntityFrameworkCore.csproj",
+      "EntityFrameworkCore\\test\\EF.InMemory.Test\\Microsoft.AspNetCore.Identity.EntityFrameworkCore.InMemory.Test.csproj",
+      "EntityFrameworkCore\\test\\EF.Test\\Microsoft.AspNetCore.Identity.EntityFrameworkCore.Test.csproj",
+      "Extensions.Core\\src\\Microsoft.Extensions.Identity.Core.csproj",
+      "Extensions.Stores\\src\\Microsoft.Extensions.Identity.Stores.csproj",
+      "Specification.Tests\\src\\Microsoft.AspNetCore.Identity.Specification.Tests.csproj",
+      "UI\\src\\Microsoft.AspNetCore.Identity.UI.csproj",
+      "samples\\IdentitySample.DefaultUI\\IdentitySample.DefaultUI.csproj",
+      "samples\\IdentitySample.Mvc\\IdentitySample.Mvc.csproj",
+      "test\\Identity.FunctionalTests\\Microsoft.AspNetCore.Identity.FunctionalTests.csproj",
+      "test\\Identity.Test\\Microsoft.AspNetCore.Identity.Test.csproj",
+      "test\\InMemory.Test\\Microsoft.AspNetCore.Identity.InMemory.Test.csproj",
+      "testassets\\Identity.DefaultUI.WebSite\\Identity.DefaultUI.WebSite.csproj"
+    ]
+  }
+}

src/Identity/UI/ref/Microsoft.AspNetCore.Identity.UI.netcoreapp3.0.cs

@@ -6,20 +6,15 @@ namespace Microsoft.AspNetCore.Identity
     public static partial class IdentityBuilderUIExtensions
     {
         public static Microsoft.AspNetCore.Identity.IdentityBuilder AddDefaultUI(this Microsoft.AspNetCore.Identity.IdentityBuilder builder) { throw null; }
-        public static Microsoft.AspNetCore.Identity.IdentityBuilder AddDefaultUI(this Microsoft.AspNetCore.Identity.IdentityBuilder builder, Microsoft.AspNetCore.Identity.UI.UIFramework framework) { throw null; }
     }
 }
 namespace Microsoft.AspNetCore.Identity.UI
 {
-    public partial class DefaultUIOptions
+    [System.AttributeUsageAttribute(System.AttributeTargets.Assembly, Inherited=false, AllowMultiple=false)]
+    public sealed partial class UIFrameworkAttribute : System.Attribute
     {
-        public DefaultUIOptions() { }
+        public UIFrameworkAttribute(string uiFramework) { }
-        public Microsoft.AspNetCore.Identity.UI.UIFramework UIFramework { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute]set { } }
+        public string UIFramework { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
-    }
-    public enum UIFramework
-    {
-        Bootstrap3 = 0,
-        Bootstrap4 = 1,
     }
 }
 namespace Microsoft.AspNetCore.Identity.UI.Services

src/Identity/UI/src/DefaultUIOptions.cs

@@ -1,16 +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.
-
-namespace Microsoft.AspNetCore.Identity.UI
-{
-    /// <summary>
-    /// Options for the default Identity UI
-    /// </summary>
-    public class DefaultUIOptions
-    {
-        /// <summary>
-        /// Gets or sets the <see cref="UIFramework"/> to use with the default UI.
-        /// </summary>
-        public UIFramework UIFramework { get; set; }
-    }
-}

src/Identity/UI/src/IdentityBuilderUIExtensions.cs

@@ -5,6 +5,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
+using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Identity.UI;
 using Microsoft.AspNetCore.Identity.UI.Services;
 using Microsoft.AspNetCore.Mvc.ApplicationModels;
@@ -30,35 +31,16 @@ namespace Microsoft.AspNetCore.Identity
         /// </remarks>
         /// <param name="builder">The <see cref="IdentityBuilder"/>.</param>
         /// <returns>The <see cref="IdentityBuilder"/>.</returns>
-        public static IdentityBuilder AddDefaultUI(this IdentityBuilder builder) => builder.AddDefaultUI(UIFramework.Bootstrap4);
+        public static IdentityBuilder AddDefaultUI(this IdentityBuilder builder)
-
-
-        /// <summary>
-        /// Adds a default, self-contained UI for Identity to the application using
-        /// Razor Pages in an area named Identity.
-        /// </summary>
-        /// <remarks>
-        /// In order to use the default UI, the application must be using <see cref="Microsoft.AspNetCore.Mvc"/>,
-        /// <see cref="Microsoft.AspNetCore.StaticFiles"/> and contain a <c>_LoginPartial</c> partial view that
-        /// can be found by the application.
-        /// </remarks>
-        /// <param name="builder">The <see cref="IdentityBuilder"/>.</param>
-        /// <param name="framework">The <see cref="UIFramework"/>.</param>
-        /// <returns>The <see cref="IdentityBuilder"/>.</returns>
-        public static IdentityBuilder AddDefaultUI(
-            this IdentityBuilder builder,
-            UIFramework framework)
         {
             builder.AddSignInManager();
-            AddRelatedParts(builder, framework);
+            AddRelatedParts(builder);
 
             builder.Services.ConfigureOptions(
                 typeof(IdentityDefaultUIConfigureOptions<>)
                     .MakeGenericType(builder.UserType));
             builder.Services.TryAddTransient<IEmailSender, EmailSender>();
 
-            builder.Services.Configure<DefaultUIOptions>(o => o.UIFramework = framework);
-
             return builder;
         }
 
@@ -69,8 +51,20 @@ namespace Microsoft.AspNetCore.Identity
                 [UIFramework.Bootstrap4] = "Microsoft.AspNetCore.Identity.UI.Views.V4",
             };
 
-        private static void AddRelatedParts(IdentityBuilder builder, UIFramework framework)
+        private static void AddRelatedParts(IdentityBuilder builder)
         {
+            // We try to resolve the UI framework that was used by looking at the entry assembly.
+            // When an app runs, the entry assembly will point to the built app. In some rare cases
+            // (functional testing) the app assembly will be different, and we'll try to locate it through
+            // the same mechanism that MVC uses today.
+            // Finally, if for some reason we aren't able to find the assembly, we'll use our default value
+            // (Bootstrap4)
+            if (!TryResolveUIFramework(Assembly.GetEntryAssembly(), out var framework) ||
+                !TryResolveUIFramework(GetApplicationAssembly(builder), out framework))
+            {
+                framework = default;
+            }
+
             var mvcBuilder = builder.Services
                 .AddMvc()
                 .ConfigureApplicationPartManager(partManager =>
@@ -131,5 +125,38 @@ namespace Microsoft.AspNetCore.Identity
                     }
                 });
         }
+
+        private static Assembly GetApplicationAssembly(IdentityBuilder builder)
+        {
+            // Whis is the same logic that MVC follows to find the application assembly.
+            var environment = builder.Services.Where(d => d.ServiceType == typeof(IWebHostEnvironment)).ToArray();
+            var applicationName = ((IWebHostEnvironment)environment.LastOrDefault()?.ImplementationInstance)
+                .ApplicationName;
+
+            var appAssembly = Assembly.Load(applicationName);
+            return appAssembly;
+        }
+
+        private static bool TryResolveUIFramework(Assembly assembly, out UIFramework uiFramework)
+        {
+            uiFramework = default;
+
+            var metadata = assembly.GetCustomAttributes<UIFrameworkAttribute>()
+                .SingleOrDefault()?.UIFramework; // Bootstrap4 is the default
+            if (metadata == null)
+            {
+                return false;
+            }
+
+            // If we find the metadata there must be a valid framework here.
+            if (!Enum.TryParse<UIFramework>(metadata, ignoreCase: true, out var uIFramework))
+            {
+                var enumValues = string.Join(", ", Enum.GetNames(typeof(UIFramework)).Select(v => $"'{v}'"));
+                throw new InvalidOperationException(
+                    $"Found an invalid value for the 'IdentityUIFrameworkVersion'. Valid values are {enumValues}");
+            }
+
+            return true;
+        }
     }
 }

src/Identity/UI/src/IdentityDefaultUIConfigureOptions.cs

@@ -3,34 +3,26 @@
 
 using System;
 using Microsoft.AspNetCore.Authentication.Cookies;
-using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Identity.UI.Areas.Identity.Filters;
 using Microsoft.AspNetCore.Mvc.RazorPages;
-using Microsoft.AspNetCore.StaticFiles;
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.FileProviders;
 using Microsoft.Extensions.Options;
 
 namespace Microsoft.AspNetCore.Identity.UI
 {
     internal class IdentityDefaultUIConfigureOptions<TUser> :
         IPostConfigureOptions<RazorPagesOptions>,
-        IPostConfigureOptions<StaticFileOptions>,
         IConfigureNamedOptions<CookieAuthenticationOptions> where TUser : class
     {
         private const string IdentityUIDefaultAreaName = "Identity";
 
         public IdentityDefaultUIConfigureOptions(
-            IWebHostEnvironment environment,
+            IWebHostEnvironment environment)        {
-            IOptions<DefaultUIOptions> uiOptions)
-        {
             Environment = environment;
-            UiOptions = uiOptions;
         }
 
         public IWebHostEnvironment Environment { get; }
-        public IOptions<DefaultUIOptions> UiOptions { get; }
 
         public void PostConfigure(string name, RazorPagesOptions options)
         {
@@ -50,30 +42,10 @@ namespace Microsoft.AspNetCore.Identity.UI
                 pam => pam.Filters.Add(new ExternalLoginsPageFilter<TUser>()));
         }
 
-        public void PostConfigure(string name, StaticFileOptions options)
+        public void Configure(CookieAuthenticationOptions options) {
-        {
+            // Nothing to do here as Configure(string name, CookieAuthenticationOptions options) is hte one setting things up.
-            name = name ?? throw new ArgumentNullException(nameof(name));
-            options = options ?? throw new ArgumentNullException(nameof(options));
-
-            // Basic initialization in case the options weren't initialized by any other component
-            options.ContentTypeProvider = options.ContentTypeProvider ?? new FileExtensionContentTypeProvider();
-            if (options.FileProvider == null && Environment.WebRootFileProvider == null)
-            {
-                throw new InvalidOperationException("Missing FileProvider.");
-            }
-
-            options.FileProvider = options.FileProvider ?? Environment.WebRootFileProvider;
-
-            var basePath = UiOptions.Value.UIFramework == UIFramework.Bootstrap3 ? "wwwroot/V3" :
-                "wwwroot/V4";
-
-            // Add our provider
-            var filesProvider = new ManifestEmbeddedFileProvider(GetType().Assembly, basePath);
-            options.FileProvider = new CompositeFileProvider(options.FileProvider, filesProvider);
         }
 
-        public void Configure(CookieAuthenticationOptions options) { }
-
         public void Configure(string name, CookieAuthenticationOptions options)
         {
             name = name ?? throw new ArgumentNullException(nameof(name));

src/Identity/UI/src/Microsoft.AspNetCore.Identity.UI.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk.Razor">
+<Project Sdk="Microsoft.NET.Sdk.Razor">
 
   <PropertyGroup>
     <Description>ASP.NET Core Identity UI is the default Razor Pages built-in UI for the ASP.NET Core Identity framework.</Description>
@@ -7,23 +7,30 @@
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageTags>aspnetcore;identity;membership;razorpages</PackageTags>
     <IsShippingPackage>true</IsShippingPackage>
-    <GenerateEmbeddedFilesManifest>true</GenerateEmbeddedFilesManifest>
     <ProvideApplicationPartFactoryAttributeTypeName>Microsoft.AspNetCore.Mvc.ApplicationParts.NullApplicationPartFactory, Microsoft.AspNetCore.Mvc.Core</ProvideApplicationPartFactoryAttributeTypeName>
     <RazorCompileOnBuild>false</RazorCompileOnBuild>
     <RazorCompileOnPublish>false</RazorCompileOnPublish>
     <EnableDefaultRazorGenerateItems>false</EnableDefaultRazorGenerateItems>
     <DisableFastUpToDateCheck>true</DisableFastUpToDateCheck>
     <AddRazorSupportForMvc>true</AddRazorSupportForMvc>
+
+    <DisableStaticWebAssetsBuildPropsFileGeneration>true</DisableStaticWebAssetsBuildPropsFileGeneration>
+    <StaticWebAssetsDisableProjectBuildPropsFileGeneration>true</StaticWebAssetsDisableProjectBuildPropsFileGeneration>
+
+    <GetCurrentProjectStaticWebAssetsDependsOn>
+      $(GetCurrentProjectStaticWebAssetsDependsOn);
+      _UpdatedIdentityUIStaticWebAssets
+    </GetCurrentProjectStaticWebAssetsDependsOn>
+
+    <IdentityUIFrameworkVersion Condition="'$(IdentityUIFrameworkVersion)' == ''">Bootstrap4</IdentityUIFrameworkVersion>
+
   </PropertyGroup>
 
   <ItemGroup>
-    <EmbeddedResource Include="wwwroot/**/*" />
+    <Content Remove="@(Content)" />
-    <EmbeddedResource Remove="wwwroot/**/LICENSE*" />
+    <Content Include="wwwroot\**\*" Pack="true" />
-    <None Remove="wwwroot/**/LICENSE*" />
+    <None Include="build\*" Pack="true" PackagePath="build\" />
     <None Include="THIRD-PARTY-NOTICES.txt" Pack="true" PackagePath="/THIRD-PARTY-NOTICES.txt" />
-
-    <Content Update="wwwroot/**/*" Pack="false" />
-    <Content Update="**\*.cshtml" Pack="false" />
   </ItemGroup>
 
   <ItemGroup>
@@ -40,6 +47,10 @@
     <UIFrameworkVersionMoniker Include="V4" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Folder Include="build\" />
+  </ItemGroup>
+
   <!-- Source build doesn't build this package -->
   <Target Name="BuildRazorViews" DependsOnTargets="Compile" BeforeTargets="Build" Condition="'$(DotNetBuildFromSource)' != 'true'">
     <Message Text="Building razor views assemblies" Importance="High" />
@@ -63,6 +74,7 @@
 
       <Output TaskParameter="DestinationFiles" ItemName="FileWrites"/>
       <Output TaskParameter="DestinationFiles" ItemName="_RazorAssembly"/>
+
     </Copy>
 
     <Copy
@@ -75,12 +87,10 @@
       UseHardlinksIfPossible="$(CreateHardLinksForCopyFilesToOutputDirectoryIfPossible)"
       UseSymboliclinksIfPossible="$(CreateSymbolicLinksForCopyFilesToOutputDirectoryIfPossible)">
 
-      <Output TaskParameter="DestinationFiles" ItemName="FileWrites"/>
+      <Output TaskParameter="DestinationFiles" ItemName="FileWrites" />
     </Copy>
 
-    <Message
+    <Message Importance="High" Text="$(MSBuildProjectName) -&gt; %(_RazorAssembly.FullPath)" />
-      Importance="High"
-      Text="$(MSBuildProjectName) -&gt; %(_RazorAssembly.FullPath)" />
 
   </Target>
 
@@ -90,19 +100,15 @@
 
   <Target Name="SetupRazorInputs">
     <ItemGroup>
-      <_RazorGenerate
+      <_RazorGenerate Include="Areas\Identity\Pages\$(UIFrameworkVersion)\**\*.cshtml" />
-        Include="Areas\Identity\Pages\$(UIFrameworkVersion)\**\*.cshtml" />
 
-      <RazorGenerate
+      <RazorGenerate Include="@(_RazorGenerate)" Link="Areas\Identity\Pages\%(RecursiveDir)%(Filename)%(Extension)" />
-        Include="@(_RazorGenerate)"
-        Link="Areas\Identity\Pages\%(RecursiveDir)%(Filename)%(Extension)" />
     </ItemGroup>
   </Target>
 
   <Target Name="BuildForUI" DependsOnTargets="SetupRazorInputs;RazorCompile" />
 
-<Target
+<Target Name="_GetRazorDlls" BeforeTargets="GetCopyToOutputDirectoryItems">
-    Name="_GetRazorDlls" BeforeTargets="GetCopyToOutputDirectoryItems">
 
     <ItemGroup>
       <_GeneratedRazorViews Include="$(TargetDir)$(TargetName).Views.%(UIFrameworkVersionMoniker.Identity).dll" />
@@ -117,15 +123,13 @@
 
   <Target Name="_AddRazorDlls" BeforeTargets="BuiltProjectOutputGroup">
     <ItemGroup>
-      <BuiltProjectOutputGroupOutput
+      <BuiltProjectOutputGroupOutput Include="$(IntermediateOutputPath)%(UIFrameworkVersionMoniker.Identity)\$(TargetName).Views.%(UIFrameworkVersionMoniker.Identity).dll" />
-        Include="$(IntermediateOutputPath)%(UIFrameworkVersionMoniker.Identity)\$(TargetName).Views.%(UIFrameworkVersionMoniker.Identity).dll" />
     </ItemGroup>
   </Target>
 
   <Target Name="_AddRazorPdbs" BeforeTargets="DebugSymbolsProjectOutputGroup">
     <ItemGroup>
-      <DebugSymbolsProjectOutputGroupOutput
+      <DebugSymbolsProjectOutputGroupOutput Include="$(IntermediateOutputPath)%(UIFrameworkVersionMoniker.Identity)\$(TargetName).Views.%(UIFrameworkVersionMoniker.Identity).pdb" />
-        Include="$(IntermediateOutputPath)%(UIFrameworkVersionMoniker.Identity)\$(TargetName).Views.%(UIFrameworkVersionMoniker.Identity).pdb" />
     </ItemGroup>
   </Target>
 
@@ -136,8 +140,34 @@
       <ExpectedOutputFile Include="$(TargetDir)Microsoft.AspNetCore.Identity.UI.Views.V4.dll" />
     </ItemGroup>
 
-    <Error Text="Unable to find precompiled view file %(ExpectedOutputFile.Identity)"
+    <Error Text="Unable to find precompiled view file %(ExpectedOutputFile.Identity)" Condition="!Exists('%(ExpectedOutputFile.Identity)')" />
-           Condition="!Exists('%(ExpectedOutputFile.Identity)')" />
+  </Target>
+
+  <Target Name="_UpdatedIdentityUIStaticWebAssets">
+
+    <ItemGroup>
+      <StaticWebAsset Remove="@(StaticWebAsset)" />
+
+      <_V3Content Include="wwwroot\V3\**" />
+      <_V4Content Include="wwwroot\V4\**" />
+
+      <StaticWebAsset Include="@(_V3Content->'%(FullPath)')" Condition="'$(IdentityUIFrameworkVersion)' == 'Bootstrap3'">
+        <SourceType></SourceType>
+        <SourceId>Microsoft.AspNetCore.Identity.UI</SourceId>
+        <ContentRoot>$([MSBuild]::NormalizePath('$(MSBuildThisFileDirectory)wwwroot/V3'))</ContentRoot>
+        <BasePath>/Identity</BasePath>
+        <RelativePath>%(RecursiveDir)%(FileName)%(Extension)</RelativePath>
+      </StaticWebAsset>
+
+      <StaticWebAsset Include="@(_V4Content->'%(FullPath)')" Condition="'$(IdentityUIFrameworkVersion)' == 'Bootstrap4'">
+        <SourceType></SourceType>
+        <SourceId>Microsoft.AspNetCore.Identity.UI</SourceId>
+        <ContentRoot>$([MSBuild]::NormalizePath('$(MSBuildThisFileDirectory)wwwroot/V4'))</ContentRoot>
+        <BasePath>/Identity</BasePath>
+        <RelativePath>%(RecursiveDir)%(FileName)%(Extension)</RelativePath>
+      </StaticWebAsset>
+    </ItemGroup>
+
   </Target>
 
 </Project>

src/Identity/UI/src/UIFramework.cs

@@ -1,21 +1,13 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// 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.
 
 namespace Microsoft.AspNetCore.Identity.UI
 {
-    /// <summary>
+    internal enum UIFramework
-    /// The list of supported presentation frameworks for the default UI
-    /// </summary>
-    public enum UIFramework
     {
-        /// <summary>
+        // The default framework for a given release must be 0.
-        /// Bootstrap 3
+        // So this needs to be updated in the future if we include more frameworks.
-        /// </summary>
+        Bootstrap4 = 0,
-        Bootstrap3 = 0,
+        Bootstrap3 = 1,
-
-        /// <summary>
-        /// Bootstrap 4
-        /// </summary>
-        Bootstrap4 = 1
     }
 }

src/Identity/UI/src/UIFrameworkAttribute.cs

@@ -0,0 +1,29 @@
+// 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.AspNetCore.Identity.UI
+{
+    /// <summary>
+    /// The UIFramework Identity UI will use on the application.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Assembly, Inherited = false, AllowMultiple = false)]
+    public sealed class UIFrameworkAttribute : Attribute
+    {
+
+        /// <summary>
+        /// Initializes a new instance of <see cref="UIFrameworkAttribute"/>.
+        /// </summary>
+        /// <param name="uiFramework"></param>
+        public UIFrameworkAttribute(string uiFramework)
+        {
+            UIFramework = uiFramework;
+        }
+
+        /// <summary>
+        /// The UI Framework Identity UI will use.
+        /// </summary>
+        public string UIFramework { get; }
+    }
+}

src/Identity/UI/src/build/Microsoft.AspNetCore.Identity.UI.props

@@ -0,0 +1,31 @@
+<Project>
+  <PropertyGroup>
+    <IdentityUIFrameworkVersion Condition="'$(IdentityUIFrameworkVersion)' == ''">Bootstrap4</IdentityUIFrameworkVersion>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <AssemblyAttribute Include="Microsoft.AspNetCore.Identity.UI.UIFrameworkAttribute">
+      <_Parameter1>$(IdentityUIFrameworkVersion)</_Parameter1>
+    </AssemblyAttribute>
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(IdentityUIFrameworkVersion)' == 'Bootstrap3'">
+    <StaticWebAsset Include="$(MSBuildThisFileDirectory)..\staticwebassets\V3\**">
+      <SourceType>Package</SourceType>
+      <SourceId>Microsoft.AspNetCore.Identity.UI</SourceId>
+      <ContentRoot>$([MSBuild]::NormalizePath('$(MSBuildThisFileDirectory)..\staticwebassets\V3'))</ContentRoot>
+      <BasePath>/Identity</BasePath>
+      <RelativePath>%(RecursiveDir)%(FileName)%(Extension)</RelativePath>
+    </StaticWebAsset>
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(IdentityUIFrameworkVersion)' == 'Bootstrap4'">
+    <StaticWebAsset Include="$(MSBuildThisFileDirectory)..\staticwebassets\V4\**">
+      <SourceType>Package</SourceType>
+      <SourceId>Microsoft.AspNetCore.Identity.UI</SourceId>
+      <ContentRoot>$([MSBuild]::NormalizePath('$(MSBuildThisFileDirectory)..\staticwebassets\V4'))</ContentRoot>
+      <BasePath>/Identity</BasePath>
+      <RelativePath>%(RecursiveDir)%(FileName)%(Extension)</RelativePath>
+    </StaticWebAsset>
+  </ItemGroup>
+</Project>

src/Identity/samples/IdentitySample.DefaultUI/Areas/Identity/Pages/_ViewStart.cshtml

@@ -1,3 +0,0 @@
-@{
-    Layout = "/Views/Shared/_Layout.cshtml";
-}

src/Identity/samples/IdentitySample.DefaultUI/IdentitySample.DefaultUI.csproj

@@ -1,12 +1,14 @@
-<Project Sdk="Microsoft.NET.Sdk.Web">
+<Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
     <Description>Identity sample MVC application on ASP.NET Core using the default UI</Description>
     <TargetFramework>netcoreapp3.0</TargetFramework>
     <UserSecretsId>aspnetcore-2ff9bc27-5e8c-4484-90ca-e3aace89b72a</UserSecretsId>
+    <IdentityUIFrameworkVersion>Bootstrap4</IdentityUIFrameworkVersion>
   </PropertyGroup>
 
   <ItemGroup>
+    <Reference Include="Microsoft.AspNetCore" />
     <Reference Include="Microsoft.AspNetCore.Authentication.Facebook" />
     <Reference Include="Microsoft.AspNetCore.Authentication.Google" />
     <Reference Include="Microsoft.AspNetCore.Authentication.Twitter" />
@@ -26,6 +28,7 @@
     <Reference Include="Microsoft.EntityFrameworkCore.Tools" PrivateAssets="All" />
     <Reference Include="Microsoft.Extensions.Configuration.EnvironmentVariables" />
     <Reference Include="Microsoft.Extensions.Configuration.UserSecrets" />
+    <Reference Include="Microsoft.Extensions.Hosting" />
     <Reference Include="Microsoft.Extensions.Logging.Console" />
     <Reference Include="Microsoft.Extensions.Logging.Debug" />
   </ItemGroup>
@@ -34,4 +37,23 @@
     <Folder Include="Properties\" />
   </ItemGroup>
 
+  <!-- Include an assembly attribute into the built application assembly to indicate which flavor of the UI framework to use -->
+  <ItemGroup>
+    <AssemblyAttribute Include="Microsoft.AspNetCore.Identity.UI.UIFrameworkAttribute">
+      <_Parameter1>$(IdentityUIFrameworkVersion)</_Parameter1>
+    </AssemblyAttribute>
+  </ItemGroup>
+
+  <PropertyGroup>
+    <ResolveStaticWebAssetsInputsDependsOn>_SetBootstrapFrameworkVersion</ResolveStaticWebAssetsInputsDependsOn>
+  </PropertyGroup>
+
+  <Target Name="_SetBootstrapFrameworkVersion">
+    <ItemGroup>
+      <_StaticWebAssetsProjectReference Condition="'%(FileName)' == 'Microsoft.AspNetCore.identity.UI'">
+        <AdditionalProperties>IdentityUIFrameworkVersion=$(IdentityUIFrameworkVersion)</AdditionalProperties>
+      </_StaticWebAssetsProjectReference>
+    </ItemGroup>
+  </Target>
+
 </Project>

src/Identity/samples/IdentitySample.DefaultUI/Program.cs

@@ -1,5 +1,6 @@
 using System.IO;
 using Microsoft.AspNetCore.Hosting;
+using Microsoft.Extensions.Hosting;
 
 namespace IdentitySample.DefaultUI
 {
@@ -7,17 +8,19 @@ namespace IdentitySample.DefaultUI
     {
         public static void Main(string[] args)
         {
-            var host = CreateWebHostBuilder(args)
+            CreateHostBuilder(args).Build().Run();
-                .Build();
-
-            host.Run();
         }
 
-        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
+        public static bool UseStartup { get; set; } = true;
-            new WebHostBuilder()
+
-                .UseKestrel()
+        public static IHostBuilder CreateHostBuilder(string[] args) =>
-                .UseContentRoot(Directory.GetCurrentDirectory())
+            Host.CreateDefaultBuilder(args)
-                .UseIISIntegration()
+                .ConfigureWebHostDefaults(webBuilder =>
-                .UseStartup<Startup>();
+                {
+                    if (UseStartup)
+                    {
+                        webBuilder.UseStartup<Startup>();
+                    }
+                });
     }
 }

src/Identity/test/Identity.FunctionalTests/Bootstrap3Tests/Bootstrap3AuthorizationTests.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// 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 Identity.DefaultUI.WebSite;
@@ -6,10 +6,11 @@ using Identity.DefaultUI.WebSite.Data;
 
 namespace Microsoft.AspNetCore.Identity.FunctionalTests.IdentityUserTests
 {
-    public class Bootstrap3AuthorizationTests : AuthorizationTests<Bootstrap3Startup, ApplicationDbContext>
+    public class Bootstrap3AuthorizationTests : AuthorizationTests<ApplicationUserStartup, ApplicationDbContext>
     {
-        public Bootstrap3AuthorizationTests(ServerFactory<Bootstrap3Startup, ApplicationDbContext> serverFactory) : base(serverFactory)
+        public Bootstrap3AuthorizationTests(ServerFactory<ApplicationUserStartup, ApplicationDbContext> serverFactory) : base(serverFactory)
         {
+            serverFactory.BootstrapFrameworkVersion = "V3";
         }
     }
 }

src/Identity/test/Identity.FunctionalTests/Bootstrap3Tests/Bootstrap3ManagementTests.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// 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 Identity.DefaultUI.WebSite;
@@ -6,10 +6,11 @@ using Identity.DefaultUI.WebSite.Data;
 
 namespace Microsoft.AspNetCore.Identity.FunctionalTests.Bootstrap3Tests
 {
-    public class Bootstrap3ManagementTests : ManagementTests<Bootstrap3Startup, ApplicationDbContext>
+    public class Bootstrap3ManagementTests : ManagementTests<ApplicationUserStartup, ApplicationDbContext>
     {
-        public Bootstrap3ManagementTests(ServerFactory<Bootstrap3Startup, ApplicationDbContext> serverFactory) : base(serverFactory)
+        public Bootstrap3ManagementTests(ServerFactory<ApplicationUserStartup, ApplicationDbContext> serverFactory) : base(serverFactory)
         {
+            serverFactory.BootstrapFrameworkVersion = "V3";
         }
     }
 }

src/Identity/test/Identity.FunctionalTests/Bootstrap3Tests/Bootstrap3RegistrationTests.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// 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 Identity.DefaultUI.WebSite;
@@ -6,10 +6,11 @@ using Identity.DefaultUI.WebSite.Data;
 
 namespace Microsoft.AspNetCore.Identity.FunctionalTests.Bootstrap3Tests
 {
-    public class Bootstrap3RegistrationTests : RegistrationTests<Bootstrap3Startup, ApplicationDbContext>
+    public class Bootstrap3RegistrationTests : RegistrationTests<ApplicationUserStartup, ApplicationDbContext>
     {
-        public Bootstrap3RegistrationTests(ServerFactory<Bootstrap3Startup, ApplicationDbContext> serverFactory) : base(serverFactory)
+        public Bootstrap3RegistrationTests(ServerFactory<ApplicationUserStartup, ApplicationDbContext> serverFactory) : base(serverFactory)
         {
+            serverFactory.BootstrapFrameworkVersion = "V3";
         }
     }
 }

src/Identity/test/Identity.FunctionalTests/Bootstrap3Tests/Bootstrap3UserLoginTests.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// 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 Identity.DefaultUI.WebSite;
@@ -6,10 +6,11 @@ using Identity.DefaultUI.WebSite.Data;
 
 namespace Microsoft.AspNetCore.Identity.FunctionalTests.Bootstrap3Tests
 {
-    public class Bootstrap3LoginTests : LoginTests<Bootstrap3Startup, ApplicationDbContext>
+    public class Bootstrap3LoginTests : LoginTests<ApplicationUserStartup, ApplicationDbContext>
     {
-        public Bootstrap3LoginTests(ServerFactory<Bootstrap3Startup, ApplicationDbContext> serverFactory) : base(serverFactory)
+        public Bootstrap3LoginTests(ServerFactory<ApplicationUserStartup, ApplicationDbContext> serverFactory) : base(serverFactory)
         {
+            serverFactory.BootstrapFrameworkVersion = "V3";
         }
     }
 }

src/Identity/test/Identity.FunctionalTests/Infrastructure/ServerFactory.cs

@@ -2,19 +2,26 @@
 // 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.IO;
+using System.Linq;
+using System.Reflection;
 using Identity.DefaultUI.WebSite;
-using Microsoft.AspNetCore.Authentication;
 using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Hosting.StaticWebAssets;
+using Microsoft.AspNetCore.Identity.UI;
+using Microsoft.AspNetCore.Mvc.ApplicationParts;
 using Microsoft.AspNetCore.Mvc.Testing;
 using Microsoft.AspNetCore.TestHost;
 using Microsoft.Data.Sqlite;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.FileProviders;
 using Microsoft.Extensions.Hosting;
 
 namespace Microsoft.AspNetCore.Identity.FunctionalTests
 {
-    public class ServerFactory<TStartup,TContext>: WebApplicationFactory<TStartup>
+    public class ServerFactory<TStartup, TContext> : WebApplicationFactory<TStartup>
         where TStartup : class
         where TContext : DbContext
     {
@@ -29,6 +36,10 @@ namespace Microsoft.AspNetCore.Identity.FunctionalTests
             ClientOptions.BaseAddress = new Uri("https://localhost");
         }
 
+        public string BootstrapFrameworkVersion { get; set; } = "V4";
+        private bool IsHelixCI => typeof(ServerFactory<,>).Assembly.GetCustomAttributes<AssemblyMetadataAttribute>()
+            .Any(a => a.Key == "Microsoft.AspNetCore.Testing.IsHelixCI");
+
         protected override IHostBuilder CreateHostBuilder()
         {
             Program.UseStartup = false;
@@ -48,6 +59,70 @@ namespace Microsoft.AspNetCore.Identity.FunctionalTests
                     // several places to pass important data in post-redirect-get flows.
                     .AddCookieTempDataProvider(o => o.Cookie.IsEssential = true);
             });
+
+            UpdateStaticAssets(builder);
+            UpdateApplicationParts(builder);
+        }
+
+        private void UpdateApplicationParts(IWebHostBuilder builder) =>
+            builder.ConfigureServices(services => AddRelatedParts(services, BootstrapFrameworkVersion));
+
+        private void UpdateStaticAssets(IWebHostBuilder builder)
+        {
+            var manifestPath = Path.GetDirectoryName(new Uri(typeof(ServerFactory<,>).Assembly.CodeBase).LocalPath);
+            builder.ConfigureAppConfiguration((ctx, cb) =>
+            {
+                if (ctx.HostingEnvironment.WebRootFileProvider is CompositeFileProvider composite)
+                {
+                    var originalWebRoot = composite.FileProviders.First();
+                    ctx.HostingEnvironment.WebRootFileProvider = originalWebRoot;
+                }
+            });
+
+            string versionedPath = Path.Combine(manifestPath, $"Testing.DefaultWebSite.StaticWebAssets.{BootstrapFrameworkVersion}.xml");
+            UpdateManifest(versionedPath);
+
+            builder.ConfigureAppConfiguration((context, configBuilder) =>
+            {
+                using (var manifest = File.OpenRead(versionedPath))
+                {
+                    typeof(StaticWebAssetsLoader)
+                        .GetMethod("UseStaticWebAssetsCore", BindingFlags.NonPublic | BindingFlags.Static)
+                        .Invoke(null, new object[] { context.HostingEnvironment, manifest });
+                }
+            });
+        }
+
+        private void UpdateManifest(string versionedPath)
+        {
+            var content = File.ReadAllText(versionedPath);
+            var path = typeof(ServerFactory<,>).Assembly.GetCustomAttributes<AssemblyMetadataAttribute>()
+                    .Single(a => a.Key == "Microsoft.AspNetCore.Testing.IdentityUIProjectPath").Value;
+
+            path = Directory.Exists(path) ? Path.Combine(path, "wwwroot") : Path.Combine(FindHelixSlnFileDirectory(), "UI", "wwwroot");
+
+            var updatedContent = content.Replace("{TEST_PLACEHOLDER}", path);
+
+            File.WriteAllText(versionedPath, updatedContent);
+        }
+
+        private string FindHelixSlnFileDirectory()
+        {
+            var applicationPath = Path.GetDirectoryName(typeof(ServerFactory<,>).Assembly.Location);
+            var directoryInfo = new DirectoryInfo(applicationPath);
+            do
+            {
+                var solutionPath = Directory.EnumerateFiles(directoryInfo.FullName, "*.sln").FirstOrDefault();
+                if (solutionPath != null)
+                {
+                    return directoryInfo.FullName;
+                }
+
+                directoryInfo = directoryInfo.Parent;
+            }
+            while (directoryInfo.Parent != null);
+
+            throw new InvalidOperationException($"Solution root could not be located using application root {applicationPath}.");
         }
 
         protected override IHost CreateHost(IHostBuilder builder)
@@ -78,5 +153,76 @@ namespace Microsoft.AspNetCore.Identity.FunctionalTests
 
             base.Dispose(disposing);
         }
+
+        private static void AddRelatedParts(IServiceCollection services, string framework)
+        {
+            var _assemblyMap =
+                new Dictionary<UIFramework, string>()
+                {
+                    [UIFramework.Bootstrap3] = "Microsoft.AspNetCore.Identity.UI.Views.V3",
+                    [UIFramework.Bootstrap4] = "Microsoft.AspNetCore.Identity.UI.Views.V4",
+                };
+
+            var mvcBuilder = services
+                .AddMvc()
+                .ConfigureApplicationPartManager(partManager =>
+                {
+                    var thisAssembly = typeof(IdentityBuilderUIExtensions).Assembly;
+                    var relatedAssemblies = RelatedAssemblyAttribute.GetRelatedAssemblies(thisAssembly, throwOnError: true);
+                    var relatedParts = relatedAssemblies.ToDictionary(
+                        ra => ra,
+                        CompiledRazorAssemblyApplicationPartFactory.GetDefaultApplicationParts);
+
+                    var selectedFrameworkAssembly = _assemblyMap[framework == "V3" ? UIFramework.Bootstrap3 : UIFramework.Bootstrap4];
+
+                    foreach (var kvp in relatedParts)
+                    {
+                        var assemblyName = kvp.Key.GetName().Name;
+                        if (!IsAssemblyForFramework(selectedFrameworkAssembly, assemblyName))
+                        {
+                            RemoveParts(partManager, kvp.Value);
+                        }
+                        else
+                        {
+                            AddParts(partManager, kvp.Value);
+                        }
+                    }
+
+                    bool IsAssemblyForFramework(string frameworkAssembly, string assemblyName) =>
+                        string.Equals(assemblyName, frameworkAssembly, StringComparison.OrdinalIgnoreCase);
+
+                    void RemoveParts(
+                        ApplicationPartManager manager,
+                        IEnumerable<ApplicationPart> partsToRemove)
+                    {
+                        for (var i = 0; i < manager.ApplicationParts.Count; i++)
+                        {
+                            var part = manager.ApplicationParts[i];
+                            if (partsToRemove.Any(p => string.Equals(
+                                    p.Name,
+                                    part.Name,
+                                    StringComparison.OrdinalIgnoreCase)))
+                            {
+                                manager.ApplicationParts.Remove(part);
+                            }
+                        }
+                    }
+
+                    void AddParts(
+                        ApplicationPartManager manager,
+                        IEnumerable<ApplicationPart> partsToAdd)
+                    {
+                        foreach (var part in partsToAdd)
+                        {
+                            if (!manager.ApplicationParts.Any(p => p.GetType() == part.GetType() &&
+                                string.Equals(p.Name, part.Name, StringComparison.OrdinalIgnoreCase)))
+                            {
+                                manager.ApplicationParts.Add(part);
+                            }
+                        }
+                    }
+                });
+        }
+
     }
 }

src/Identity/test/Identity.FunctionalTests/Microsoft.AspNetCore.Identity.FunctionalTests.csproj

@@ -10,6 +10,7 @@
 
     <Compile Include="..\..\Extensions.Core\src\Base32.cs" Link="Infrastructure\Base32.cs" />
     <Compile Include="..\..\Extensions.Core\src\Rfc6238AuthenticationService.cs" Link="Infrastructure\Rfc6238AuthenticationService.cs" />
+    <Compile Include="..\..\UI\src\UIFramework.cs" Link="Infrastructure\UIFramework.cs" />
   </ItemGroup>
 
   <ItemGroup>
@@ -27,6 +28,39 @@
     <Reference Include="AngleSharp" />
   </ItemGroup>
 
+  <ItemGroup>
+    <None Update="Testing.DefaultWebSite.StaticWebAssets.V4.xml">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+    <None Update="Testing.DefaultWebSite.StaticWebAssets.V4.xml">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+    <None Update="Testing.DefaultWebSite.StaticWebAssets.V3.xml">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+
+  <Target Name="AddProjectReferenceAssemblyInfo" BeforeTargets="GetAssemblyAttributes" DependsOnTargets="ResolveAssemblyReferences">
+    <ItemGroup>
+      <_IdentitUIDefaultWebSite Include="@(ReferencePath)" Condition="'%(ReferencePath.FileName)' == 'Identity.DefaultUI.WebSite'" />
+      <AssemblyAttribute Include="System.Reflection.AssemblyMetadataAttribute">
+        <_Parameter1>Microsoft.AspNetCore.Testing.DefaultWebSiteProjectPath</_Parameter1>
+        <_Parameter2>$([System.IO.Path]::GetDirectoryName('%(_IdentitUIDefaultWebSite.MSBuildSourceProjectFile)'))</_Parameter2>
+      </AssemblyAttribute>
+
+      <_IdentitUIProjectPath Include="@(ReferencePath)" Condition="'%(ReferencePath.FileName)' == 'Microsoft.AspNetCore.Identity.UI'" />
+      <AssemblyAttribute Include="System.Reflection.AssemblyMetadataAttribute">
+        <_Parameter1>Microsoft.AspNetCore.Testing.IdentityUIProjectPath</_Parameter1>
+        <_Parameter2>$([System.IO.Path]::GetDirectoryName('%(_IdentitUIProjectPath.MSBuildSourceProjectFile)'))</_Parameter2>
+      </AssemblyAttribute>
+
+      <AssemblyAttribute Include="System.Reflection.AssemblyMetadataAttribute" Condition="'$(HelixType)' == 'ci'">
+        <_Parameter1>Microsoft.AspNetCore.Testing.IsHelixCI</_Parameter1>
+        <_Parameter2>true</_Parameter2>
+      </AssemblyAttribute>
+    </ItemGroup>
+  </Target>
+
   <Target Name="PublishAssets" AfterTargets="Publish">
     <ItemGroup>
       <_PublishFiles Include="$(ArtifactsBinDir)Microsoft.AspNetCore.Identity.UI\$(Configuration)\netcoreapp3.0\Microsoft.AspNetCore.Identity.UI.Views.*.dll" />
@@ -34,22 +68,16 @@
       <_PublishFiles Include="$(ArtifactsBinDir)Identity.DefaultUI.WebSite\$(Configuration)\netcoreapp3.0\Identity.DefaultUI.WebSite.deps.json" />
       <_wwwrootFiles Include="$(MSBuildThisFileDirectory)..\..\testassets\Identity.DefaultUI.WebSite\wwwroot\**\*.*" />
       <_PagesFiles Include="$(MSBuildThisFileDirectory)..\..\testassets\Identity.DefaultUI.WebSite\Pages\**\*.*" />
+      <_IdentityUIContent Include="$(MSBuildThisFileDirectory)..\..\UI\src\wwwroot\**\*" />
+      <_IdentityUIPages Include="$(MSBuildThisFileDirectory)..\..\UI\src\Areas\Identity\Pages\**\*" />
     </ItemGroup>
-    <Copy
+    <Copy SourceFiles="@(_PublishFiles)" DestinationFolder="$(PublishDir)" />
-      SourceFiles="@(_PublishFiles)"
+    <Copy SourceFiles="@(_PagesFiles)" DestinationFolder="$(PublishDir)\Identity.DefaultUI.WebSite\Pages" />
-      DestinationFolder="$(PublishDir)" />
+    <Copy SourceFiles="@(_wwwrootFiles)" DestinationFolder="$(PublishDir)\Identity.DefaultUI.WebSite\wwwroot" />
-    <Copy
+    <Copy SourceFiles="@(_IdentityUIContent)" DestinationFiles="$(PublishDir)\UI\wwwroot\%(_IdentityUIContent.RecursiveDir)\%(_IdentityUIContent.FileName)%(_IdentityUIContent.Extension)" />
-      SourceFiles="@(_PagesFiles)"
+    <Copy SourceFiles="@(_IdentityUIPages)" DestinationFiles="$(PublishDir)UI\Areas\Identity\Pages\%(_IdentityUIPages.RecursiveDir)\%(_IdentityUIPages.FileName)%(_IdentityUIPages.Extension)" />
-      DestinationFolder="$(PublishDir)\Identity.DefaultUI.WebSite\Pages" />
-    <Copy
-      SourceFiles="@(_wwwrootFiles)"
-      DestinationFolder="$(PublishDir)\Identity.DefaultUI.WebSite\wwwroot" />
     <!-- Drop a dummy sln to specify content root location -->
-    <WriteLinesToFile
+    <WriteLinesToFile File="$(PublishDir)\contentroot.sln" Lines="Ignored" Overwrite="true" Encoding="Unicode" />
-        File="$(PublishDir)\contentroot.sln"
-        Lines="Ignored"
-        Overwrite="true"
-        Encoding="Unicode" />
   </Target>
 
 </Project>

src/Identity/test/Identity.FunctionalTests/Testing.DefaultWebSite.StaticWebAssets.V3.xml

@@ -0,0 +1,3 @@
+<StaticWebAssets Version="1.0">
+  <ContentRoot BasePath="/Identity" Path="{TEST_PLACEHOLDER}/V3" />
+</StaticWebAssets>

src/Identity/test/Identity.FunctionalTests/Testing.DefaultWebSite.StaticWebAssets.V4.xml

@@ -0,0 +1,3 @@
+<StaticWebAssets Version="1.0">
+  <ContentRoot BasePath="/Identity" Path="{TEST_PLACEHOLDER}/V4" />
+</StaticWebAssets>

src/Identity/test/Identity.Test/IdentityUIScriptsTest.cs

@@ -15,6 +15,7 @@ using Microsoft.AspNetCore.Testing;
 using Microsoft.AspNetCore.Testing.xunit;
 using Xunit;
 using Xunit.Abstractions;
+using System.Reflection;
 
 namespace Microsoft.AspNetCore.Identity.Test
 {
@@ -83,11 +84,11 @@ namespace Microsoft.AspNetCore.Identity.Test
         [Flaky("https://github.com/aspnet/AspNetCore-Internal/issues/2267", FlakyOn.AzP.macOS)]
         public async Task IdentityUI_ScriptTags_FallbackSourceContent_Matches_CDNContent(ScriptTag scriptTag)
         {
-            var wwwrootDir = Path.Combine(AppContext.BaseDirectory, "UI", "src", "wwwroot", scriptTag.Version);
+            var wwwrootDir = Path.Combine(GetProjectBasePath(), "wwwroot", scriptTag.Version);
 
             var cdnContent = await _httpClient.GetStringAsync(scriptTag.Src);
             var fallbackSrcContent = File.ReadAllText(
-                Path.Combine(wwwrootDir, scriptTag.FallbackSrc.TrimStart('~').TrimStart('/')));
+                Path.Combine(wwwrootDir, scriptTag.FallbackSrc.Replace("Identity", "").TrimStart('~').TrimStart('/')));
 
             Assert.Equal(RemoveLineEndings(cdnContent), RemoveLineEndings(fallbackSrcContent));
         }
@@ -108,8 +109,8 @@ namespace Microsoft.AspNetCore.Identity.Test
 
         private static List<ScriptTag> GetScriptTags()
         {
-            var uiDirV3 = Path.Combine(AppContext.BaseDirectory, "UI", "src", "Areas", "Identity", "Pages", "V3");
+            var uiDirV3 = Path.Combine(GetProjectBasePath(), "Areas", "Identity", "Pages", "V3");
-            var uiDirV4 = Path.Combine(AppContext.BaseDirectory, "UI", "src", "Areas", "Identity", "Pages", "V4");
+            var uiDirV4 = Path.Combine(GetProjectBasePath(), "Areas", "Identity", "Pages", "V4");
             var cshtmlFiles = GetRazorFiles(uiDirV3).Concat(GetRazorFiles(uiDirV4));
 
             var scriptTags = new List<ScriptTag>();
@@ -163,6 +164,32 @@ namespace Microsoft.AspNetCore.Identity.Test
             _httpClient.Dispose();
         }
 
+        private static string GetProjectBasePath()
+        {
+            var projectPath = typeof(IdentityUIScriptsTest).Assembly.GetCustomAttributes<AssemblyMetadataAttribute>()
+                .Single(a => a.Key == "Microsoft.AspNetCore.Testing.DefaultUIProjectPath").Value;
+            return Directory.Exists(projectPath) ? projectPath : Path.Combine(FindHelixSlnFileDirectory(), "UI");
+        }
+
+        private static string FindHelixSlnFileDirectory()
+        {
+            var applicationPath = Path.GetDirectoryName(typeof(IdentityUIScriptsTest).Assembly.Location);
+            var directoryInfo = new DirectoryInfo(applicationPath);
+            do
+            {
+                var solutionPath = Directory.EnumerateFiles(directoryInfo.FullName, "*.sln").FirstOrDefault();
+                if (solutionPath != null)
+                {
+                    return directoryInfo.FullName;
+                }
+
+                directoryInfo = directoryInfo.Parent;
+            }
+            while (directoryInfo.Parent != null);
+
+            throw new InvalidOperationException($"Solution root could not be located using application root {applicationPath}.");
+        }
+
         class RetryHandler : DelegatingHandler
         {
             public RetryHandler(HttpMessageHandler innerHandler) : base(innerHandler) { }

src/Identity/test/Identity.Test/Microsoft.AspNetCore.Identity.Test.csproj

@@ -7,8 +7,6 @@
   <ItemGroup>
     <Compile Include="$(IdentityTestSharedSourceRoot)**\*.cs" />
     <Compile Include="$(SharedSourceRoot)test\SkipOnHelixAttribute.cs" />
-    <Content Include="..\..\UI\src\Areas\Identity\Pages\**\*.*" LinkBase="UI\src\Areas\Identity\Pages" />
-    <Content Include="..\..\UI\src\wwwroot\**\*.*" LinkBase="UI\src\wwwroot" />
   </ItemGroup>
 
   <ItemGroup>
@@ -17,8 +15,31 @@
     <Reference Include="Microsoft.AspNetCore.Http" />
     <Reference Include="Microsoft.AspNetCore.Identity.Specification.Tests" />
     <Reference Include="Microsoft.AspNetCore.Identity" />
+    <Reference Include="Microsoft.AspNetCore.Identity.UI" />
     <Reference Include="Microsoft.Extensions.Configuration" />
     <Reference Include="Microsoft.Extensions.Options.ConfigurationExtensions" />
   </ItemGroup>
 
+  <Target Name="AddProjectReferenceAssemblyInfo" BeforeTargets="GetAssemblyAttributes" DependsOnTargets="ResolveAssemblyReferences">
+    <ItemGroup>
+      <_IdentitUIDefaultUI Include="@(ReferencePath)" Condition="'%(ReferencePath.FileName)' == 'Microsoft.AspNetCore.Identity.UI'" />
+      <AssemblyAttribute Include="System.Reflection.AssemblyMetadataAttribute">
+        <_Parameter1>Microsoft.AspNetCore.Testing.DefaultUIProjectPath</_Parameter1>
+        <_Parameter2>$([System.IO.Path]::GetDirectoryName('%(_IdentitUIDefaultUI.MSBuildSourceProjectFile)'))</_Parameter2>
+      </AssemblyAttribute>      
+    </ItemGroup>
+  </Target>
+
+  <Target Name="PublishAssets" AfterTargets="Publish">
+    <ItemGroup>
+      <_IdentityUIContent Include="$(MSBuildThisFileDirectory)..\..\UI\src\wwwroot\**\*" />
+      <_IdentityUIPages Include="$(MSBuildThisFileDirectory)..\..\UI\src\Areas\Identity\Pages\**\*" />
+    </ItemGroup>
+    <Copy SourceFiles="@(_IdentityUIContent)" DestinationFiles="$(PublishDir)\UI\wwwroot\%(_IdentityUIContent.RecursiveDir)\%(_IdentityUIContent.FileName)%(_IdentityUIContent.Extension)" />
+    <Copy SourceFiles="@(_IdentityUIPages)" DestinationFiles="$(PublishDir)UI\Areas\Identity\Pages\%(_IdentityUIPages.RecursiveDir)\%(_IdentityUIPages.FileName)%(_IdentityUIPages.Extension)" />
+    <!-- Drop a dummy sln to specify content root location -->
+    <WriteLinesToFile File="$(PublishDir)\contentroot.sln" Lines="Ignored" Overwrite="true" Encoding="Unicode" />
+  </Target>
+
+
 </Project>

src/Identity/testassets/Identity.DefaultUI.WebSite/Bootstrap3Startup.cs

@@ -1,19 +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.AspNetCore.Identity;
-using Microsoft.AspNetCore.Identity.UI;
-using Microsoft.Extensions.Configuration;
-using Microsoft.Extensions.DependencyInjection;
-
-namespace Identity.DefaultUI.WebSite
-{
-    public class Bootstrap3Startup : ApplicationUserStartup
-    {
-        public Bootstrap3Startup(IConfiguration configuration) : base(configuration)
-        {
-        }
-
-        public override UIFramework Framework => UIFramework.Bootstrap3;
-    }
-}

src/Identity/testassets/Identity.DefaultUI.WebSite/Identity.DefaultUI.WebSite.csproj

@@ -3,6 +3,7 @@
   <PropertyGroup>
     <TargetFramework>netcoreapp3.0</TargetFramework>
     <UserSecretsId>aspnet-Identity.DefaultUI.WebSite-80C658D8-CED7-467F-9B47-75DA3BC1A16D</UserSecretsId>
+    <IdentityDefaultUIFramework>Bootstrap3</IdentityDefaultUIFramework>
   </PropertyGroup>
 
   <ItemGroup>
@@ -43,4 +44,15 @@
     <Reference Include="Microsoft.Extensions.Logging.Debug" />
   </ItemGroup>
 
+  <PropertyGroup>
+    <ResolveStaticWebAssetsInputsDependsOn>_SetBootstrapFrameworkVersion</ResolveStaticWebAssetsInputsDependsOn>
+  </PropertyGroup>
+
+  <Target Name="_SetBootstrapFrameworkVersion">
+    <ItemGroup>
+      <_StaticWebAssetsProjectReference Condition="'%(FileName)' == 'Microsoft.AspNetCore.Identity.UI'">
+        <AdditionalProperties>IdentityDefaultUIFramework=$(IdentityDefaultUIFramework)</AdditionalProperties>
+      </_StaticWebAssetsProjectReference>
+    </ItemGroup>
+  </Target>
 </Project>

src/Identity/testassets/Identity.DefaultUI.WebSite/PocoUserStartup.cs

@@ -27,7 +27,6 @@ namespace Identity.DefaultUI.WebSite
             });
 
             services.AddDefaultIdentity<Microsoft.AspNetCore.Identity.Test.PocoUser>()
-                .AddDefaultUI(UIFramework.Bootstrap4)
                 .AddUserManager<UserManager<Microsoft.AspNetCore.Identity.Test.PocoUser>>();
             services.AddSingleton<IUserStore<Microsoft.AspNetCore.Identity.Test.PocoUser>, InMemoryUserStore<Microsoft.AspNetCore.Identity.Test.PocoUser>>();
 

src/Identity/testassets/Identity.DefaultUI.WebSite/StartupBase.cs

@@ -28,8 +28,6 @@ namespace Identity.DefaultUI.WebSite
 
         public IConfiguration Configuration { get; }
 
-        public virtual UIFramework Framework { get; } = UIFramework.Bootstrap4;
-
         // This method gets called by the runtime. Use this method to add services to the container.
         public virtual void ConfigureServices(IServiceCollection services)
         {
@@ -49,7 +47,6 @@ namespace Identity.DefaultUI.WebSite
                     .UseSqlite("DataSource=:memory:"));
 
             services.AddDefaultIdentity<TUser>()
-                .AddDefaultUI(Framework)
                 .AddRoles<IdentityRole>()
                 .AddEntityFrameworkStores<TContext>();
                 

src/ProjectTemplates/test/Helpers/Project.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
@@ -41,11 +42,19 @@ namespace Templates.Test.Helpers
         public ITestOutputHelper Output { get; set; }
         public IMessageSink DiagnosticsMessageSink { get; set; }
 
-        internal async Task<ProcessEx> RunDotNetNewAsync(string templateName, string auth = null, string language = null, bool useLocalDB = false, bool noHttps = false, string[] args = null)
+        internal async Task<ProcessEx> RunDotNetNewAsync(
+            string templateName,
+            string auth = null,
+            string language = null,
+            bool useLocalDB = false,
+            bool noHttps = false,
+            string[] args = null,
+            // Used to set special options in MSBuild
+            IDictionary<string, string> environmentVariables = null)
         {
             var hiveArg = $"--debug:custom-hive \"{TemplatePackageInstaller.CustomHivePath}\"";
             var argString = $"new {templateName} {hiveArg}";
-
+            environmentVariables ??= new Dictionary<string, string>();
             if (!string.IsNullOrEmpty(auth))
             {
                 argString += $" --auth {auth}";
@@ -86,7 +95,7 @@ namespace Templates.Test.Helpers
             await DotNetNewLock.WaitAsync();
             try
             {
-                var execution = ProcessEx.Run(Output, AppContext.BaseDirectory, DotNetMuxer.MuxerPathOrDefault(), argString);
+                var execution = ProcessEx.Run(Output, AppContext.BaseDirectory, DotNetMuxer.MuxerPathOrDefault(), argString, environmentVariables);
                 await execution.Exited;
                 return execution;
             }
@@ -96,7 +105,7 @@ namespace Templates.Test.Helpers
             }
         }
 
-        internal async Task<ProcessEx> RunDotNetPublishAsync(bool takeNodeLock = false)
+        internal async Task<ProcessEx> RunDotNetPublishAsync(bool takeNodeLock = false, IDictionary<string,string> packageOptions = null)
         {
             Output.WriteLine("Publishing ASP.NET application...");
 
@@ -112,7 +121,7 @@ namespace Templates.Test.Helpers
             await effectiveLock.WaitAsync();
             try
             {
-                var result = ProcessEx.Run(Output, TemplateOutputDir, DotNetMuxer.MuxerPathOrDefault(), $"publish -c Release {extraArgs}");
+                var result = ProcessEx.Run(Output, TemplateOutputDir, DotNetMuxer.MuxerPathOrDefault(), $"publish -c Release {extraArgs}", packageOptions);
                 await result.Exited;
                 return result;
             }
@@ -122,7 +131,7 @@ namespace Templates.Test.Helpers
             }
         }
 
-        internal async Task<ProcessEx> RunDotNetBuildAsync(bool takeNodeLock = false)
+        internal async Task<ProcessEx> RunDotNetBuildAsync(bool takeNodeLock = false, IDictionary<string,string> packageOptions = null)
         {
             Output.WriteLine("Building ASP.NET application...");
 
@@ -133,7 +142,7 @@ namespace Templates.Test.Helpers
             await effectiveLock.WaitAsync();
             try
             {
-                var result = ProcessEx.Run(Output, TemplateOutputDir, DotNetMuxer.MuxerPathOrDefault(), "build -c Debug");
+                var result = ProcessEx.Run(Output, TemplateOutputDir, DotNetMuxer.MuxerPathOrDefault(), "build -c Debug", packageOptions);
                 await result.Exited;
                 return result;
             }

src/ProjectTemplates/test/IdentityUIPackageTest.cs

@@ -0,0 +1,190 @@
+// 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.Collections.Generic;
+using System.IO;
+using System.Net;
+using System.Threading.Tasks;
+using Templates.Test.Helpers;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace Templates.Test
+{
+    public class IdentityUIPackageTest
+    {
+        public IdentityUIPackageTest(ProjectFactoryFixture projectFactory, ITestOutputHelper output)
+        {
+            ProjectFactory = projectFactory;
+            Output = output;
+        }
+
+        public Project Project { get; set; }
+
+        public ProjectFactoryFixture ProjectFactory { get; set; }
+
+        public ITestOutputHelper Output { get; }
+
+        public static TheoryData<IDictionary<string, string>, string, string[]> MSBuildIdentityUIPackageOptions
+        {
+            get
+            {
+                var data = new TheoryData<IDictionary<string, string>, string, string[]>();
+
+                data.Add(new Dictionary<string, string>
+                {
+                    ["IdentityUIFrameworkVersion"] = "Bootstrap3"
+                },
+                "Bootstrap v3.4.1",
+                Bootstrap3ContentFiles);
+
+                data.Add(new Dictionary<string, string>(), "Bootstrap v4.3.1", Bootstrap4ContentFiles);
+
+                return data;
+            }
+        }
+
+        public static string[] Bootstrap3ContentFiles { get; } = new string[]
+        {
+            "Identity/css/site.css",
+            "Identity/js/site.js",
+            "Identity/lib/bootstrap/dist/css/bootstrap-theme.css",
+            "Identity/lib/bootstrap/dist/css/bootstrap-theme.css.map",
+            "Identity/lib/bootstrap/dist/css/bootstrap-theme.min.css",
+            "Identity/lib/bootstrap/dist/css/bootstrap-theme.min.css.map",
+            "Identity/lib/bootstrap/dist/css/bootstrap.css",
+            "Identity/lib/bootstrap/dist/css/bootstrap.css.map",
+            "Identity/lib/bootstrap/dist/css/bootstrap.min.css",
+            "Identity/lib/bootstrap/dist/css/bootstrap.min.css.map",
+            "Identity/lib/bootstrap/dist/fonts/glyphicons-halflings-regular.eot",
+            "Identity/lib/bootstrap/dist/fonts/glyphicons-halflings-regular.svg",
+            "Identity/lib/bootstrap/dist/fonts/glyphicons-halflings-regular.ttf",
+            "Identity/lib/bootstrap/dist/fonts/glyphicons-halflings-regular.woff",
+            "Identity/lib/bootstrap/dist/fonts/glyphicons-halflings-regular.woff2",
+            "Identity/lib/bootstrap/dist/js/bootstrap.js",
+            "Identity/lib/bootstrap/dist/js/bootstrap.min.js",
+            "Identity/lib/bootstrap/dist/js/npm.js",
+            "Identity/lib/jquery/LICENSE.txt",
+            "Identity/lib/jquery/dist/jquery.js",
+            "Identity/lib/jquery/dist/jquery.min.js",
+            "Identity/lib/jquery/dist/jquery.min.map",
+            "Identity/lib/jquery-validation/LICENSE.md",
+            "Identity/lib/jquery-validation/dist/additional-methods.js",
+            "Identity/lib/jquery-validation/dist/additional-methods.min.js",
+            "Identity/lib/jquery-validation/dist/jquery.validate.js",
+            "Identity/lib/jquery-validation/dist/jquery.validate.min.js",
+            "Identity/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.js",
+            "Identity/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.min.js",
+            "Identity/lib/jquery-validation-unobtrusive/LICENSE.txt",
+        };
+
+        public static string[] Bootstrap4ContentFiles { get; } = new string[]
+        {
+            "Identity/favicon.ico",
+            "Identity/css/site.css",
+            "Identity/js/site.js",
+            "Identity/lib/bootstrap/dist/css/bootstrap-grid.css",
+            "Identity/lib/bootstrap/dist/css/bootstrap-grid.css.map",
+            "Identity/lib/bootstrap/dist/css/bootstrap-grid.min.css",
+            "Identity/lib/bootstrap/dist/css/bootstrap-grid.min.css.map",
+            "Identity/lib/bootstrap/dist/css/bootstrap-reboot.css",
+            "Identity/lib/bootstrap/dist/css/bootstrap-reboot.css.map",
+            "Identity/lib/bootstrap/dist/css/bootstrap-reboot.min.css",
+            "Identity/lib/bootstrap/dist/css/bootstrap-reboot.min.css.map",
+            "Identity/lib/bootstrap/dist/css/bootstrap.css",
+            "Identity/lib/bootstrap/dist/css/bootstrap.css.map",
+            "Identity/lib/bootstrap/dist/css/bootstrap.min.css",
+            "Identity/lib/bootstrap/dist/css/bootstrap.min.css.map",
+            "Identity/lib/bootstrap/dist/js/bootstrap.bundle.js",
+            "Identity/lib/bootstrap/dist/js/bootstrap.bundle.js.map",
+            "Identity/lib/bootstrap/dist/js/bootstrap.bundle.min.js",
+            "Identity/lib/bootstrap/dist/js/bootstrap.bundle.min.js.map",
+            "Identity/lib/bootstrap/dist/js/bootstrap.js",
+            "Identity/lib/bootstrap/dist/js/bootstrap.js.map",
+            "Identity/lib/bootstrap/dist/js/bootstrap.min.js",
+            "Identity/lib/bootstrap/dist/js/bootstrap.min.js.map",
+            "Identity/lib/jquery/LICENSE.txt",
+            "Identity/lib/jquery/dist/jquery.js",
+            "Identity/lib/jquery/dist/jquery.min.js",
+            "Identity/lib/jquery/dist/jquery.min.map",
+            "Identity/lib/jquery-validation/LICENSE.md",
+            "Identity/lib/jquery-validation/dist/additional-methods.js",
+            "Identity/lib/jquery-validation/dist/additional-methods.min.js",
+            "Identity/lib/jquery-validation/dist/jquery.validate.js",
+            "Identity/lib/jquery-validation/dist/jquery.validate.min.js",
+            "Identity/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.js",
+            "Identity/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.min.js",
+            "Identity/lib/jquery-validation-unobtrusive/LICENSE.txt",
+        };
+
+        [Theory]
+        [MemberData(nameof(MSBuildIdentityUIPackageOptions))]
+        public async Task IdentityUIPackage_WorksWithDifferentOptions(IDictionary<string, string> packageOptions, string versionValidator, string[] expectedFiles)
+        {
+            Project = await ProjectFactory.GetOrCreateProject("identityuipackage" + string.Concat(packageOptions.Values), Output);
+            var useLocalDB = false;
+
+            var createResult = await Project.RunDotNetNewAsync("razor", auth: "Individual", useLocalDB: useLocalDB, environmentVariables: packageOptions);
+            Assert.True(0 == createResult.ExitCode, ErrorMessages.GetFailedProcessMessage("create/restore", Project, createResult));
+
+            var projectFileContents = ReadFile(Project.TemplateOutputDir, $"{Project.ProjectName}.csproj");
+            Assert.Contains(".db", projectFileContents);
+
+            var publishResult = await Project.RunDotNetPublishAsync(packageOptions: packageOptions);
+            Assert.True(0 == publishResult.ExitCode, ErrorMessages.GetFailedProcessMessage("publish", Project, publishResult));
+
+            // Run dotnet build after publish. The reason is that one uses Config = Debug and the other uses Config = Release
+            // The output from publish will go into bin/Release/netcoreapp3.0/publish and won't be affected by calling build
+            // later, while the opposite is not true.
+
+            var buildResult = await Project.RunDotNetBuildAsync(packageOptions: packageOptions);
+            Assert.True(0 == buildResult.ExitCode, ErrorMessages.GetFailedProcessMessage("build", Project, buildResult));
+
+            var migrationsResult = await Project.RunDotNetEfCreateMigrationAsync("razorpages");
+            Assert.True(0 == migrationsResult.ExitCode, ErrorMessages.GetFailedProcessMessage("run EF migrations", Project, migrationsResult));
+            Project.AssertEmptyMigration("razorpages");
+
+            using (var aspNetProcess = Project.StartBuiltProjectAsync())
+            {
+                Assert.False(
+                    aspNetProcess.Process.HasExited,
+                    ErrorMessages.GetFailedProcessMessageOrEmpty("Run built project", Project, aspNetProcess.Process));
+
+                var response = await aspNetProcess.SendRequest("/Identity/lib/bootstrap/dist/css/bootstrap.css");
+                Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+                Assert.Contains(versionValidator, await response.Content.ReadAsStringAsync());
+                await ValidatePublishedFiles(aspNetProcess, expectedFiles);
+            }
+
+            using (var aspNetProcess = Project.StartPublishedProjectAsync())
+            {
+                Assert.False(
+                    aspNetProcess.Process.HasExited,
+                    ErrorMessages.GetFailedProcessMessageOrEmpty("Run built project", Project, aspNetProcess.Process));
+
+                var response = await aspNetProcess.SendRequest("/Identity/lib/bootstrap/dist/css/bootstrap.css");
+                Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+                Assert.Contains(versionValidator, await response.Content.ReadAsStringAsync());
+                await ValidatePublishedFiles(aspNetProcess, expectedFiles);
+            }
+        }
+
+        private async Task ValidatePublishedFiles(AspNetProcess aspNetProcess, string[] expectedContentFiles)
+        {
+            foreach (var file in expectedContentFiles)
+            {
+                var response = await aspNetProcess.SendRequest(file);
+                Assert.True(response?.StatusCode == HttpStatusCode.OK, $"Couldn't find file '{file}'");
+            }
+        }
+
+        private string ReadFile(string basePath, string path)
+        {
+            var fullPath = Path.Combine(basePath, path);
+            var doesExist = File.Exists(fullPath);
+
+            Assert.True(doesExist, $"Expected file to exist, but it doesn't: {path}");
+            return File.ReadAllText(Path.Combine(basePath, path));
+        }
+    }
+}