[Blazor] Fixes publishing for standalone blazor-wasm applications (#17353)

* Updates the publish path on the static web assets to match the convention used by standalone blazor applications.

src/Components/Blazor/Build/src/targets/All.targets

@@ -17,6 +17,7 @@
 
   <Import Project="Blazor.MonoRuntime.targets" />
   <Import Project="Publish.targets" />
+  <Import Project="StaticWebAssets.targets" />
 
   <Target Name="GenerateBlazorMetadataFile"
     BeforeTargets="GetCopyToOutputDirectoryItems">
@@ -42,17 +43,4 @@
     </ItemGroup>
   </Target>
 
-  <PropertyGroup>
-    <GetCurrentProjectStaticWebAssetsDependsOn>
-      $(GetCurrentProjectStaticWebAssetsDependsOn);
-      _ClearCurrentStaticWebAssetsForReferenceDiscovery
-    </GetCurrentProjectStaticWebAssetsDependsOn>
-  </PropertyGroup>
-
-  <Target Name="_ClearCurrentStaticWebAssetsForReferenceDiscovery">
-    <ItemGroup>
-      <StaticWebAsset Remove="@(StaticWebAsset)" Condition="'%(SourceType)' == ''" />
-    </ItemGroup>
-  </Target>
-
 </Project>

src/Components/Blazor/Build/src/targets/StaticWebAssets.targets

@@ -0,0 +1,32 @@
+<Project>
+
+  <PropertyGroup>
+    <ResolveStaticWebAssetsInputsDependsOn>
+      $(ResolveStaticWebAssetsInputsDependsOn);
+      _RemoveBlazorCurrentProjectAssetsFromStaticWebAssets;
+    </ResolveStaticWebAssetsInputsDependsOn>
+  </PropertyGroup>
+
+
+  <Target Name="_RemoveBlazorCurrentProjectAssetsFromStaticWebAssets">
+    <ItemGroup>
+      <StaticWebAsset Remove="@(StaticWebAsset)" Condition="'%(SourceType)' == ''" />
+    </ItemGroup>
+  </Target>
+
+  <Target Name="BlazorStaticWebAssetsComputeFilesToPublish"
+    AfterTargets="_StaticWebAssetsComputeFilesToPublish">
+
+    <ItemGroup>
+      <!-- We need to update the external static web assets to follow the blazor publish output convention that puts them inside $(TargetName)/dist instead of wwwroot -->
+      <_StandaloneExternalPublishStaticWebAsset Include="@(_ExternalPublishStaticWebAsset)" Condition="'%(RelativePath)' != ''">
+        <RelativePath>$([MSBuild]::MakeRelative('$(MSBuildProjectDirectory)', '$([MSBuild]::NormalizePath('$([System.Text.RegularExpressions.Regex]::Replace('%(RelativePath)','^wwwroot\\?\/?(.*)','$(BlazorPublishDistDir)$1'))'))'))</RelativePath>
+      </_StandaloneExternalPublishStaticWebAsset>
+
+      <!-- Update doesn't work inside targets so we need to remove the items and re-add them. See https://github.com/microsoft/msbuild/issues/2835 for details -->
+      <ResolvedFileToPublish Remove="@(_StandaloneExternalPublishStaticWebAsset)" />
+      <ResolvedFileToPublish Include="@(_StandaloneExternalPublishStaticWebAsset)" />
+
+    </ItemGroup>
+  </Target>
+</Project>

src/Components/Blazor/Build/test/BuildIntegrationTests/PublishIntegrationTest.cs

@@ -13,7 +13,7 @@ namespace Microsoft.AspNetCore.Blazor.Build
         public async Task Publish_WithDefaultSettings_Works()
         {
             // Arrange
-            using var project = ProjectDirectory.Create("standalone");
+            using var project = ProjectDirectory.Create("standalone", additionalProjects: new string[] { "razorclasslibrary" });
             var result = await MSBuildProcessManager.DotnetMSBuild(project, "Publish");
 
             Assert.BuildPassed(result);
@@ -28,6 +28,10 @@ namespace Microsoft.AspNetCore.Blazor.Build
             Assert.FileExists(result, blazorPublishDirectory, "dist", "_framework", "_bin", "standalone.dll");
             Assert.FileExists(result, blazorPublishDirectory, "dist", "_framework", "_bin", "Microsoft.Extensions.Logging.Abstractions.dll"); // Verify dependencies are part of the output.
 
+            // Verify referenced static web assets
+            Assert.FileExists(result, blazorPublishDirectory, "dist", "_content", "RazorClassLibrary", "wwwroot", "exampleJsInterop.js");
+            Assert.FileExists(result, blazorPublishDirectory, "dist", "_content", "RazorClassLibrary", "styles.css");
+
             // Verify static assets are in the publish directory
             Assert.FileExists(result, blazorPublishDirectory, "dist", "index.html");
 
@@ -39,7 +43,7 @@ namespace Microsoft.AspNetCore.Blazor.Build
         public async Task Publish_WithLinkOnBuildDisabled_Works()
         {
             // Arrange
-            using var project = ProjectDirectory.Create("standalone");
+            using var project = ProjectDirectory.Create("standalone", additionalProjects: new string[] { "razorclasslibrary" });
             project.AddProjectFileContent(
 @"<PropertyGroup>
     <BlazorLinkOnBuild>false</BlazorLinkOnBuild>
@@ -62,6 +66,10 @@ namespace Microsoft.AspNetCore.Blazor.Build
             // Verify static assets are in the publish directory
             Assert.FileExists(result, blazorPublishDirectory, "dist", "index.html");
 
+            // Verify referenced static web assets
+            Assert.FileExists(result, blazorPublishDirectory, "dist", "_content", "RazorClassLibrary", "wwwroot", "exampleJsInterop.js");
+            Assert.FileExists(result, blazorPublishDirectory, "dist", "_content", "RazorClassLibrary", "styles.css");
+
             // Verify web.config
             Assert.FileExists(result, publishDirectory, "web.config");
         }

src/Components/Blazor/Build/testassets/razorclasslibrary/RazorClassLibrary.csproj

@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk.Razor">
+
+  <PropertyGroup>
+    <TargetFramework>netstandard2.1</TargetFramework>
+    <RazorLangVersion>3.0</RazorLangVersion>
+  </PropertyGroup>
+
+</Project>

src/Components/Blazor/Build/testassets/razorclasslibrary/wwwroot/styles.css

@@ -0,0 +1 @@
+

src/Components/Blazor/Build/testassets/standalone/standalone.csproj

@@ -13,4 +13,8 @@
     <PackageReference Include="Microsoft.AspNetCore.Blazor.Mono" Version="$(MicrosoftAspNetCoreBlazorMonoPackageVersion)" />
   </ItemGroup>
 
+  <ItemGroup>
+    <ProjectReference Include="..\razorclasslibrary\RazorClassLibrary.csproj" />
+  </ItemGroup>
+
 </Project>

src/Components/Blazor/testassets/HostedInAspNet.Client/HostedInAspNet.Client.csproj

@@ -11,17 +11,4 @@
     <Reference Include="Microsoft.AspNetCore.Blazor" />
   </ItemGroup>
 
-  <PropertyGroup>
-    <GetCurrentProjectStaticWebAssetsDependsOn>
-      $(GetCurrentProjectStaticWebAssetsDependsOn);
-      _ClearCurrentStaticWebAssetsForReferenceDiscovery
-    </GetCurrentProjectStaticWebAssetsDependsOn>
-  </PropertyGroup>
-
-  <Target Name="_ClearCurrentStaticWebAssetsForReferenceDiscovery">
-    <ItemGroup>
-      <StaticWebAsset Remove="@(StaticWebAsset)" Condition="'%(SourceType)' == ''" />
-    </ItemGroup>
-  </Target>
-
 </Project>