Point MSTest.Sdk back to the classic sourcegen + engine wiring

Restore the MSTestEngineVersion property and re-add the MSTest.Engine package reference in the NativeAOT engine, referencing both MSTest.Engine and MSTest.SourceGeneration at that version (as in 4.2.3), while keeping the 4.3 packaging/CPM/SDK-layering improvements and report extensions.

Since MSTest.Engine and MSTest.SourceGeneration are no longer built from this repo, hardcode the version to the last co-published preview (2.0.0-alpha.26264.3) so consumer projects always resolve a real package instead of an unpublished -dev/-ci build.

Also drop the 4.3-only MSTest.TestAdapter reference and the EnableMSTestRunner/IsTestingPlatformApplication property group from the NativeAOT runner. Those were added for the new source generator; with the classic MSTest.Engine they caused a second test framework to be registered ('The test framework adapter factory has already been registered'). Restoring the 4.2 wiring (MSTest.Engine + MSTest.SourceGeneration only) fixes NativeAot_Smoke_Test, verified locally.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: Evangelink

src/Package/MSTest.Sdk/MSTest.Sdk.csproj

@@ -46,13 +46,6 @@
   <Target Name="GenerateTemplates" AfterTargets="PrepareForBuild">
     <PropertyGroup>
       <!-- https://github.com/dotnet/arcade/blob/cb9979d0e7061c2252f4a3057c20eb72f503cff7/src/Microsoft.DotNet.Arcade.Sdk/tools/Version.BeforeCommonTargets.targets#L111-L114 -->
-      <_MSTestSourceGenerationPreReleaseVersionLabel>$(MSTestSourceGenerationPreReleaseVersionLabel)</_MSTestSourceGenerationPreReleaseVersionLabel>
-      <_MSTestSourceGenerationPreReleaseVersionLabel Condition="'$(ContinuousIntegrationBuild)' == 'true' and '$(OfficialBuild)' != 'true'">ci</_MSTestSourceGenerationPreReleaseVersionLabel>
-      <_MSTestSourceGenerationPreReleaseVersionLabel Condition="'$(ContinuousIntegrationBuild)' != 'true' and '$(OfficialBuild)' != 'true'">dev</_MSTestSourceGenerationPreReleaseVersionLabel>
-      <_MSTestSourceGenerationVersionSuffix>$(_MSTestSourceGenerationPreReleaseVersionLabel)$(_BuildNumberLabels)</_MSTestSourceGenerationVersionSuffix>
-      <_MSTestSourceGenerationVersion>$(MSTestSourceGenerationVersionPrefix)</_MSTestSourceGenerationVersion>
-      <_MSTestSourceGenerationVersion Condition="'$(_MSTestSourceGenerationVersionSuffix)' != ''">$(_MSTestSourceGenerationVersion)-$(_MSTestSourceGenerationVersionSuffix)</_MSTestSourceGenerationVersion>
-
       <_MicrosoftTestingExtensionsCtrfReportPreReleaseVersionLabel>$(MicrosoftTestingExtensionsCtrfReportPreReleaseVersionLabel)</_MicrosoftTestingExtensionsCtrfReportPreReleaseVersionLabel>
       <_MicrosoftTestingExtensionsCtrfReportPreReleaseVersionLabel Condition="'$(ContinuousIntegrationBuild)' == 'true' and '$(OfficialBuild)' != 'true'">ci</_MicrosoftTestingExtensionsCtrfReportPreReleaseVersionLabel>
       <_MicrosoftTestingExtensionsCtrfReportPreReleaseVersionLabel Condition="'$(ContinuousIntegrationBuild)' != 'true' and '$(OfficialBuild)' != 'true'">dev</_MicrosoftTestingExtensionsCtrfReportPreReleaseVersionLabel>
@@ -81,7 +74,7 @@
       <_MicrosoftTestingExtensionsOpenTelemetryVersion>$(MicrosoftTestingExtensionsOpenTelemetryVersionPrefix)</_MicrosoftTestingExtensionsOpenTelemetryVersion>
       <_MicrosoftTestingExtensionsOpenTelemetryVersion Condition="'$(_MicrosoftTestingExtensionsOpenTelemetryVersionSuffix)' != ''">$(_MicrosoftTestingExtensionsOpenTelemetryVersion)-$(_MicrosoftTestingExtensionsOpenTelemetryVersionSuffix)</_MicrosoftTestingExtensionsOpenTelemetryVersion>
 
-      <_TemplateProperties>MSTestSourceGenerationVersion=$(_MSTestSourceGenerationVersion);MSTestVersion=$(Version);MicrosoftTestingPlatformVersion=$(Version.Replace('$(VersionPrefix)', '$(TestingPlatformVersionPrefix)'));MicrosoftNETTestSdkVersion=$(MicrosoftNETTestSdkVersion);MicrosoftTestingExtensionsCodeCoverageVersion=$(MicrosoftTestingExtensionsCodeCoverageVersion);MicrosoftPlaywrightVersion=$(MicrosoftPlaywrightVersion);AspireHostingTestingVersion=$(AspireHostingTestingVersion);MicrosoftTestingExtensionsFakesVersion=$(MicrosoftTestingExtensionsFakesVersion);MicrosoftTestingExtensionsCtrfReportVersion=$(_MicrosoftTestingExtensionsCtrfReportVersion);MicrosoftTestingExtensionsJUnitReportVersion=$(_MicrosoftTestingExtensionsJUnitReportVersion);MicrosoftTestingExtensionsGitHubActionsReportVersion=$(_MicrosoftTestingExtensionsGitHubActionsReportVersion);MicrosoftTestingExtensionsOpenTelemetryVersion=$(_MicrosoftTestingExtensionsOpenTelemetryVersion)</_TemplateProperties>
+      <_TemplateProperties>MSTestVersion=$(Version);MicrosoftTestingPlatformVersion=$(Version.Replace('$(VersionPrefix)', '$(TestingPlatformVersionPrefix)'));MicrosoftNETTestSdkVersion=$(MicrosoftNETTestSdkVersion);MicrosoftTestingExtensionsCodeCoverageVersion=$(MicrosoftTestingExtensionsCodeCoverageVersion);MicrosoftPlaywrightVersion=$(MicrosoftPlaywrightVersion);AspireHostingTestingVersion=$(AspireHostingTestingVersion);MicrosoftTestingExtensionsFakesVersion=$(MicrosoftTestingExtensionsFakesVersion);MicrosoftTestingExtensionsCtrfReportVersion=$(_MicrosoftTestingExtensionsCtrfReportVersion);MicrosoftTestingExtensionsJUnitReportVersion=$(_MicrosoftTestingExtensionsJUnitReportVersion);MicrosoftTestingExtensionsGitHubActionsReportVersion=$(_MicrosoftTestingExtensionsGitHubActionsReportVersion);MicrosoftTestingExtensionsOpenTelemetryVersion=$(_MicrosoftTestingExtensionsOpenTelemetryVersion)</_TemplateProperties>
     </PropertyGroup>
 
     <!--

src/Package/MSTest.Sdk/Sdk/Runner/NativeAOT.targets

@@ -3,19 +3,6 @@
 
   <Import Project="$(MSBuildThisFileDirectory)Common.targets"/>
 
-  <PropertyGroup Condition=" '$(IsTestApplication)' == 'true' ">
-    <EnableMSTestRunner>true</EnableMSTestRunner>
-
-    <!-- When we are using mstest sdk-style project, we have IsTestingPlatformApplication set to false, thus it's causing issues.
-    Because we are setting this property based on EnableMSTestRunner which is set to false,
-    because of the order of import (mstest testadapter props then NativeAOT.targets),
-    we need to set IsTestingPlatformApplication to true in NativeAOT.targets to fix this issue.
-
-    The IsTestingPlatformApplication property is needed for the dotnet test driver to distinguish
-    if we need to run the test project using the new testing platform. -->
-    <IsTestingPlatformApplication>true</IsTestingPlatformApplication>
-  </PropertyGroup>
-
   <Target Name="_MSTestSDKValidateFeatures" BeforeTargets="Build">
     <Error Condition=" '$(EnableAspireTesting)' == 'true' " Text="Aspire MSTest currently doesn't support NativeAOT mode." />
     <Error Condition=" '$(EnablePlaywright)' == 'true' " Text="Playwright MSTest currently doesn't support NativeAOT mode." />
@@ -43,10 +30,16 @@
     <PackageVersion Include="MSTest.TestFramework" Version="$(MSTestVersion)"
                     Condition=" '$(ManagePackageVersionsCentrally)' == 'true' " />
 
+    <PackageReference Include="MSTest.Engine" Sdk="MSTest">
+      <Version Condition=" '$(ManagePackageVersionsCentrally)' != 'true' ">$(MSTestEngineVersion)</Version>
+    </PackageReference>
+    <PackageVersion Include="MSTest.Engine" Version="$(MSTestEngineVersion)"
+                    Condition=" '$(ManagePackageVersionsCentrally)' == 'true' " />
+
     <PackageReference Include="MSTest.SourceGeneration" Sdk="MSTest">
-      <Version Condition=" '$(ManagePackageVersionsCentrally)' != 'true' ">$(MSTestSourceGenerationVersion)</Version>
+      <Version Condition=" '$(ManagePackageVersionsCentrally)' != 'true' ">$(MSTestEngineVersion)</Version>
     </PackageReference>
-    <PackageVersion Include="MSTest.SourceGeneration" Version="$(MSTestSourceGenerationVersion)"
+    <PackageVersion Include="MSTest.SourceGeneration" Version="$(MSTestEngineVersion)"
                     Condition=" '$(ManagePackageVersionsCentrally)' == 'true' " />
   </ItemGroup>
 
@@ -64,17 +57,6 @@
     </PackageReference>
     <PackageVersion Include="Microsoft.Testing.Platform" Version="$(MicrosoftTestingPlatformVersion)"
                     Condition=" '$(EnableMicrosoftTestingPlatform)' == 'true' and '$(ManagePackageVersionsCentrally)' == 'true' " />
-
-    <!--
-      MSTest.TestAdapter is required because it carries MSTestAdapter.PlatformServices.dll which
-      contains the runtime hook types (ReflectionMetadataHook, SourceGeneratedReflectionDataProvider)
-      that the MSTest.SourceGeneration analyzer emits calls into.
-      -->
-    <PackageReference Include="MSTest.TestAdapter" Sdk="MSTest">
-      <Version Condition=" '$(ManagePackageVersionsCentrally)' != 'true' ">$(MSTestVersion)</Version>
-    </PackageReference>
-    <PackageVersion Include="MSTest.TestAdapter" Version="$(MSTestVersion)"
-                    Condition=" '$(ManagePackageVersionsCentrally)' == 'true' " />
   </ItemGroup>
 
   <!-- Extensions -->

src/Package/MSTest.Sdk/Sdk/Sdk.props.template

@@ -51,7 +51,12 @@
     <MicrosoftTestingExtensionsJUnitReportVersion Condition=" '$(MicrosoftTestingExtensionsJUnitReportVersion)' == '' " >${MicrosoftTestingExtensionsJUnitReportVersion}</MicrosoftTestingExtensionsJUnitReportVersion>
     <MicrosoftTestingExtensionsOpenTelemetryVersion Condition=" '$(MicrosoftTestingExtensionsOpenTelemetryVersion)' == '' " >${MicrosoftTestingExtensionsOpenTelemetryVersion}</MicrosoftTestingExtensionsOpenTelemetryVersion>
     <MicrosoftTestingPlatformVersion Condition=" '$(MicrosoftTestingPlatformVersion)' == '' " >${MicrosoftTestingPlatformVersion}</MicrosoftTestingPlatformVersion>
-    <MSTestSourceGenerationVersion Condition=" '$(MSTestSourceGenerationVersion)' == '' ">${MSTestSourceGenerationVersion}</MSTestSourceGenerationVersion>
+    <!--
+      MSTest.Engine and MSTest.SourceGeneration are no longer built from this repo. Pin to the last
+      co-published preview so NativeAOT/source-gen projects resolve a real package on all build kinds
+      (a computed version would produce an unpublished -dev/-ci suffix). Overridable by the consumer.
+    -->
+    <MSTestEngineVersion Condition=" '$(MSTestEngineVersion)' == '' ">2.0.0-alpha.26264.3</MSTestEngineVersion>
     <MSTestVersion Condition=" '$(MSTestVersion)' == '' ">${MSTestVersion}</MSTestVersion>
   </PropertyGroup>