build: migrate tests to Microsoft.Testing.Platform v2

.config/dotnet-tools.json

@@ -10,7 +10,7 @@
       "rollForward": false
     },
     "csharpier": {
-      "version": "1.2.6",
+      "version": "1.3.0",
       "commands": [
         "csharpier"
       ],

.github/workflows/build-test-core.yml

@@ -76,8 +76,47 @@ jobs:
       - name: Build
         run: dotnet build Scribe.slnx --configuration Release --no-restore
 
+      # Microsoft.Testing.Platform: tests are self-hosting executables driven by the MTP
+      # `dotnet test` (opted in via global.json `test.runner`). xUnit's built-in reporter
+      # emits CTRF test results (no extra package); the CodeCoverage extension emits
+      # Cobertura. Both are rendered below; the report steps run on always() so a test
+      # failure still publishes results while the Test step's exit code fails the job.
       - name: Test
-        run: dotnet test Scribe.slnx --configuration Release --no-build --verbosity normal --logger "trx;LogFileName=test-results.trx"
+        run: >-
+          dotnet test --solution Scribe.slnx --configuration Release --no-build --verbosity normal
+          --
+          --report-ctrf --report-ctrf-filename test-results.ctrf.json
+          --coverage --coverage-output-format cobertura --coverage-output coverage.cobertura.xml
+
+      - name: Publish test report
+        if: always()
+        continue-on-error: true
+        uses: ctrf-io/github-test-reporter@v1
+        with:
+          report-path: '**/test-results.ctrf.json'
+
+      - name: Generate coverage report
+        if: always()
+        continue-on-error: true
+        uses: danielpalme/ReportGenerator-GitHub-Action@5
+        with:
+          reports: '**/coverage.cobertura.xml'
+          targetdir: coveragereport
+          reporttypes: MarkdownSummaryGithub;Html
+
+      - name: Publish coverage summary
+        if: always()
+        run: |
+          if [ -f coveragereport/SummaryGithub.md ]; then
+            cat coveragereport/SummaryGithub.md >> "$GITHUB_STEP_SUMMARY"
+          fi
+
+      - name: Upload coverage report
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage-report
+          path: coveragereport
 
       - name: Pack core packages
         if: github.event_name == 'push' || github.event_name == 'workflow_dispatch'
@@ -86,13 +125,6 @@ jobs:
           dotnet pack Scribe.Ink/Scribe.Ink.csproj     --configuration Release --no-build --output .artifacts/packages
           dotnet pack Scribe.Scriptorium/Scribe.Scriptorium.csproj --configuration Release --no-build --output .artifacts/packages
 
-      - name: Upload test results
-        if: always()
-        uses: actions/upload-artifact@v4
-        with:
-          name: test-results-core
-          path: "**/test-results.trx"
-
       - name: Upload packages
         if: github.event_name == 'push' || github.event_name == 'workflow_dispatch'
         uses: actions/upload-artifact@v4

Directory.Build.props

@@ -12,6 +12,8 @@
   <PropertyGroup Condition="$(MSBuildProjectName.EndsWith('.Tests'))">
     <IsTestProject>true</IsTestProject>
     <IsPackable>false</IsPackable>
+    <!-- Microsoft.Testing.Platform test projects are executables (they host the in-proc runner). -->
+    <OutputType>Exe</OutputType>
     <TargetFramework>net10.0</TargetFramework>
     <LangVersion>preview</LangVersion>
     <ImplicitUsings>enable</ImplicitUsings>

Directory.Packages.props

@@ -9,20 +9,19 @@
     <!-- Versioning — applied globally to all Scribe projects. -->
     <GlobalPackageReference Include="Nerdbank.GitVersioning" Version="3.9.50" PrivateAssets="all" />
     <!-- SourceLink — embeds GitHub source pointers in PDBs so consumers can step through source. -->
-    <GlobalPackageReference Include="Microsoft.SourceLink.GitHub" Version="10.0.201" PrivateAssets="all" />
+    <GlobalPackageReference Include="Microsoft.SourceLink.GitHub" Version="10.0.300" PrivateAssets="all" />
   </ItemGroup>
   <ItemGroup>
     <!-- Roslyn SDK — used by Scribe. -->
     <PackageVersion Include="Microsoft.CodeAnalysis.Common" Version="5.3.0" />
     <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="5.3.0" />
     <PackageVersion Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="5.3.0" />
-    <!-- Test dependencies -->
+    <!-- Test dependencies. xunit.v3.mtp-v2 hosts on Microsoft.Testing.Platform v2 (no VSTest SDK
+         or runner.visualstudio); CodeCoverage is the native MTP coverage collector. -->
     <PackageVersion Include="Bogus" Version="35.6.5" />
-    <PackageVersion Include="coverlet.collector" Version="8.0.1" />
-    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.3.0" />
+    <PackageVersion Include="Microsoft.Testing.Extensions.CodeCoverage" Version="18.8.0" />
     <PackageVersion Include="Moq" Version="4.20.72" />
     <PackageVersion Include="Shouldly" Version="4.3.0" />
-    <PackageVersion Include="xunit.v3" Version="3.2.2" />
-    <PackageVersion Include="xunit.runner.visualstudio" Version="3.1.5" />
+    <PackageVersion Include="xunit.v3.mtp-v2" Version="3.2.2" />
   </ItemGroup>
-</Project>
+</Project>

Scribe.Tests/OutputDirectoryAssemblyResolver.cs

@@ -0,0 +1,45 @@
+using System.Runtime.Loader;
+using Xunit.v3;
+
+[assembly: TestPipelineStartup(typeof(Scribe.Tests.OutputDirectoryAssemblyResolver))]
+
+namespace Scribe.Tests;
+
+/// <summary>
+///     Microsoft.Testing.Platform runs this test project as a self-hosted executable that
+///     resolves runtime assemblies strictly from its <c>.deps.json</c>. Scribe is consumed
+///     here via a <c>ProjectReference</c> to a Scribe.Sdk <c>Library</c> project, whose output
+///     is intentionally kept out of consumers' runtime dependency graph — in production it
+///     ships embedded as an analyzer, loaded by the Roslyn host, never as an application
+///     runtime dependency. VSTest's <c>testhost</c> masked this by probing the output
+///     directory; MTP does not, so a test that instantiates a generator touching Scribe throws
+///     <see cref="System.IO.FileNotFoundException"/>.
+///
+///     Installed via xUnit's pipeline-startup hook rather than a <c>[ModuleInitializer]</c>:
+///     the Scribe.Sdk injects polyfilled <c>ModuleInitializerAttribute</c> types into both
+///     <c>Scribe</c> and <c>Scribe.Ink</c>, which collide here via <c>InternalsVisibleTo</c>.
+///     The assemblies sit in the output directory regardless; this teaches the default load
+///     context to probe there for anything missing from the deps.json graph.
+/// </summary>
+public sealed class OutputDirectoryAssemblyResolver : ITestPipelineStartup
+{
+    public ValueTask StartAsync(Xunit.Sdk.IMessageSink diagnosticMessageSink)
+    {
+        AssemblyLoadContext.Default.Resolving += static (context, assemblyName) =>
+        {
+            if (assemblyName.Name is not { } name)
+            {
+                return null;
+            }
+
+            var candidate = Path.Combine(AppContext.BaseDirectory, name + ".dll");
+            return File.Exists(candidate)
+                ? context.LoadFromAssemblyPath(candidate)
+                : null;
+        };
+
+        return default;
+    }
+
+    public ValueTask StopAsync() => default;
+}

Scribe.Tests/Scribe.Tests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <ItemGroup>
     <ProjectReference Include="..\Scribe\Scribe.csproj" />
     <ProjectReference Include="..\Scribe.Ink\Scribe.Ink.csproj" />
@@ -7,9 +7,30 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" />
+    <PackageReference Include="Microsoft.Testing.Extensions.CodeCoverage" />
     <PackageReference Include="Shouldly" />
-    <PackageReference Include="xunit.v3" />
-    <PackageReference Include="xunit.runner.visualstudio" />
+    <PackageReference Include="xunit.v3.mtp-v2" />
   </ItemGroup>
+
+  <!--
+    Microsoft.CodeAnalysis.CSharp 5.x (netstandard2.0) transitively pulls in the netstandard2.0
+    builds of several system libraries (System.Threading.Tasks.Extensions, System.Collections.Immutable,
+    System.Memory, …). The .NET 10 framework also provides 10.x versions, so any type present in both
+    — e.g. ValueTask, used by xUnit's ITestPipelineStartup in OutputDirectoryAssemblyResolver — raises a
+    CS0433 ambiguous-type error. All listed assemblies are binary-compatible and the framework copy wins at
+    runtime. Strip the .nuget-cached netstandard2.0 copies from ReferencePath, keeping the framework copies.
+    (Same workaround as Hermetic.Logos.Tests.)
+  -->
+  <PropertyGroup>
+    <_AmbiguousNetStandardSystemRefs>;System.Buffers.dll;System.Collections.Immutable.dll;System.Memory.dll;System.Numerics.Vectors.dll;System.Reflection.Metadata.dll;System.Runtime.CompilerServices.Unsafe.dll;System.Text.Encoding.CodePages.dll;System.Threading.Tasks.Extensions.dll;</_AmbiguousNetStandardSystemRefs>
+  </PropertyGroup>
+  <Target Name="RemoveAmbiguousNetStandardSystemRefs" AfterTargets="ResolveAssemblyReferences">
+    <ItemGroup>
+      <ReferencePath
+        Remove="@(ReferencePath)"
+        Condition="$(_AmbiguousNetStandardSystemRefs.Contains(';%(FileName)%(Extension);'))
+                                and $([System.String]::Copy('%(Identity)').Contains('.nuget'))"
+      />
+    </ItemGroup>
+  </Target>
 </Project>

Scribe.slnx

@@ -1,6 +1,11 @@
 <Solution>
   <Project Path="Scribe/Scribe.csproj" />
   <Folder Name="/Solution Items/">
+    <File Path=".config/dotnet-tools.json" />
+    <File Path="Directory.Build.props" />
+    <File Path="Directory.Build.targets" />
+    <File Path="Directory.Packages.props" />
+    <File Path="global.json" />
     <File Path="version.json" />
   </Folder>
   <Project Path="Scribe.Ink/Scribe.Ink.csproj" />

global.json

@@ -5,6 +5,9 @@
     "allowPrerelease": false
   },
   "msbuild-sdks": {
-    "BulletsForHumanity.Scribe.Sdk": "0.6.4"
+    "BulletsForHumanity.Scribe.Sdk": "0.6.6"
+  },
+  "test": {
+    "runner": "Microsoft.Testing.Platform"
   }
 }