Keep WebView modules fallback project-local

src/Components/WebView/WebView/src/StaticWebAssets.Groups.targets

@@ -7,7 +7,8 @@
        Purpose: WebView apps fetch _framework/blazor.modules.json at runtime. When the app
        contributes its own JS library modules, the SDK generates that manifest. When it does
        not, nothing would be served, so this package ships an empty ([]) fallback and
-       materializes it as the consumer's own static web asset ONLY in that case. The decision is
+       materializes it as the consumer's own current-project-only static web asset ONLY in that
+       case. The fallback does not flow from libraries to referencing projects. The decision is
        made here, during ResolveStaticWebAssetsInputs (before the build manifest is generated and
        its conflict check runs), so exactly one asset ever lands on the route and no group /
        conflict-resolution machinery is required. -->
@@ -53,7 +54,7 @@
       ContentRoot="$(_BlazorWebViewModulesFallbackRoot)"
       BasePath="/"
       AssetKind="All"
-      AssetMode="All"
+      AssetMode="CurrentProject"
       AssetRole="Primary"
       FingerprintCandidates="true">
       <Output TaskParameter="Assets" ItemName="_BlazorWebViewModulesFallbackAsset" />

src/Components/WebView/test/StaticWebAssets/ConsumerBuild.cs

@@ -50,6 +50,9 @@ public ConsumerBuild(ITestOutputHelper output, bool isolateNuGetFeeds = true, [C
         // fallback so the exact transitive package versions the repo restored (which may not be
         // published to public feeds yet) can still be resolved.
         var repoCache = StaticWebAssetsTestData.NuGetPackageRoot.TrimEnd('\\', '/');
+        var nonShippingSource = Directory.Exists(StaticWebAssetsTestData.NonShippingPackagesDir)
+            ? $"""<add key="local-nonshipping" value="{StaticWebAssetsTestData.NonShippingPackagesDir.TrimEnd('\\', '/')}" />"""
+            : "";
         File.WriteAllText(Path.Combine(_root, "NuGet.config"), $"""
             <configuration>
               <config>
@@ -62,7 +65,7 @@ public ConsumerBuild(ITestOutputHelper output, bool isolateNuGetFeeds = true, [C
               <packageSources>
                 <clear />
                 <add key="local-shipping" value="{StaticWebAssetsTestData.ShippingPackagesDir.TrimEnd('\\', '/')}" />
-                <add key="local-nonshipping" value="{StaticWebAssetsTestData.NonShippingPackagesDir.TrimEnd('\\', '/')}" />
+                {nonShippingSource}
                 <add key="dotnet-public" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-public/nuget/v3/index.json" />
                 <add key="nuget" value="https://api.nuget.org/v3/index.json" />
               </packageSources>
@@ -201,9 +204,9 @@ internal sealed record ProcessResult(int ExitCode, string Output, string BinlogP
     /// </summary>
     public bool LooksLikeNetworkFailure
         => !Succeeded &&
+           !Output.Contains("The local source", StringComparison.OrdinalIgnoreCase) &&
            (Output.Contains("Unable to load the service index", StringComparison.OrdinalIgnoreCase) ||
             Output.Contains("NU1301", StringComparison.OrdinalIgnoreCase) ||
-            Output.Contains("Unable to resolve", StringComparison.OrdinalIgnoreCase) && Output.Contains("nuget", StringComparison.OrdinalIgnoreCase) ||
             Output.Contains("The remote name could not be resolved", StringComparison.OrdinalIgnoreCase) ||
             Output.Contains("No such host is known", StringComparison.OrdinalIgnoreCase));
 }

src/Components/WebView/test/StaticWebAssets/WebViewBuildBehaviorTests.cs

@@ -118,6 +118,103 @@ public void PublishAndBuild_AppWithoutJsModules_ServesEmptyFallbackModulesManife
         Assert.Equal("[]", File.ReadAllText(publishedManifest!).Trim());
     }
 
+    [ConditionalFact]
+    public void Publish_AppAndRclWithoutJsModulesBothReferencingWebView_ProducesSingleFallbackManifest()
+    {
+        using var build = new ConsumerBuild(_output);
+
+        build.CreateProject("rcl", "rcl.csproj", $"""
+            <Project Sdk="Microsoft.NET.Sdk.Razor">
+              <PropertyGroup>
+                <TargetFramework>{StaticWebAssetsTestData.DefaultTargetFramework}</TargetFramework>
+              </PropertyGroup>
+              <ItemGroup>
+                <PackageReference Include="Microsoft.AspNetCore.Components.WebView" Version="{StaticWebAssetsTestData.PackageVersion}" />
+              </ItemGroup>
+            </Project>
+            """);
+
+        build.CreateProject("app", "app.csproj", $"""
+            <Project Sdk="Microsoft.NET.Sdk.Razor">
+              <PropertyGroup>
+                <TargetFramework>{StaticWebAssetsTestData.DefaultTargetFramework}</TargetFramework>
+                <OutputType>Exe</OutputType>
+              </PropertyGroup>
+              <ItemGroup>
+                <PackageReference Include="Microsoft.AspNetCore.Components.WebView" Version="{StaticWebAssetsTestData.PackageVersion}" />
+                <ProjectReference Include="..\rcl\rcl.csproj" />
+              </ItemGroup>
+            </Project>
+            """);
+        build.CreateFile("app/Program.cs", "class Program { static void Main() { } }");
+
+        var result = build.Run("publish -c Release -v:m", "app/app.csproj");
+        if (result.LooksLikeNetworkFailure)
+        {
+            return;
+        }
+
+        Assert.True(result.Succeeded, $"Publish should succeed.\n{result.Output}");
+        Assert.DoesNotContain("Conflicting assets with the same target path", result.Output);
+
+        var routes = GetModulesManifestRoutes(build.Root);
+        Assert.Equal("_framework/blazor.modules.json", Assert.Single(routes));
+
+        var publishedManifest = FindPublishedFile(build.Root, "blazor.modules.json");
+        Assert.NotNull(publishedManifest);
+        Assert.Equal("[]", File.ReadAllText(publishedManifest!).Trim());
+    }
+
+    [ConditionalFact]
+    public void Publish_AppAndRclWithJsModulesBothReferencingWebView_ProducesSingleModulesManifest()
+    {
+        using var build = new ConsumerBuild(_output);
+
+        build.CreateProject("rcl", "rcl.csproj", $"""
+            <Project Sdk="Microsoft.NET.Sdk.Razor">
+              <PropertyGroup>
+                <TargetFramework>{StaticWebAssetsTestData.DefaultTargetFramework}</TargetFramework>
+              </PropertyGroup>
+              <ItemGroup>
+                <PackageReference Include="Microsoft.AspNetCore.Components.WebView" Version="{StaticWebAssetsTestData.PackageVersion}" />
+              </ItemGroup>
+            </Project>
+            """);
+        build.CreateFile("rcl/wwwroot/rcl.lib.module.js", "export function afterStarted() {}");
+
+        build.CreateProject("app", "app.csproj", $"""
+            <Project Sdk="Microsoft.NET.Sdk.Razor">
+              <PropertyGroup>
+                <TargetFramework>{StaticWebAssetsTestData.DefaultTargetFramework}</TargetFramework>
+                <OutputType>Exe</OutputType>
+              </PropertyGroup>
+              <ItemGroup>
+                <PackageReference Include="Microsoft.AspNetCore.Components.WebView" Version="{StaticWebAssetsTestData.PackageVersion}" />
+                <ProjectReference Include="..\rcl\rcl.csproj" />
+              </ItemGroup>
+            </Project>
+            """);
+        build.CreateFile("app/Program.cs", "class Program { static void Main() { } }");
+
+        var result = build.Run("publish -c Release -v:m", "app/app.csproj");
+        if (result.LooksLikeNetworkFailure)
+        {
+            return;
+        }
+
+        Assert.True(result.Succeeded, $"Publish should succeed.\n{result.Output}");
+        Assert.DoesNotContain("Conflicting assets with the same target path", result.Output);
+
+        var routes = GetModulesManifestRoutes(build.Root);
+        Assert.Equal("_framework/blazor.modules.json", Assert.Single(routes));
+
+        var publishedManifest = FindPublishedFile(build.Root, "blazor.modules.json");
+        Assert.NotNull(publishedManifest);
+        var publishedContent = File.ReadAllText(publishedManifest!);
+        Assert.Contains("_content/rcl/", publishedContent);
+        Assert.Contains(".lib.module.js", publishedContent);
+    }
+
     [ConditionalFact]
     public void Publish_ProjectReferenceToWebViewWithJsModuleRcl_SucceedsWithSingleModulesManifest()
     {