From 962135549025c7e13d2d2dacee0d6c24a2b95648 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Amaury=20Lev=C3=A9?= <amauryleve@microsoft.com>
Date: Tue, 14 Jul 2026 15:54:39 +0200
Subject: [PATCH] Restore InternalsVisibleTo for deprecated MSTest.Engine to
 fix MethodAccessException

The previously shipped MSTest.Engine package (assembly name Microsoft.Testing.Framework) calls internal platform members such as ArgumentGuard.Ensure. The InternalsVisibleTo grants for Microsoft.Testing.Framework / MSTest.Engine were dropped in #2615 during the rename to Microsoft.Testing.Internal.Framework, causing a System.MethodAccessException at runtime when the old engine binary is loaded against the newer platform (see #9769). Restoring the grants keeps binary compatibility, mirroring the TestRequestExecutionTimeInfo workaround.

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

Copilot-Session: 32680b56-ae8b-4df9-bf5d-d6be9a1a3dc4
---
 .../Microsoft.Testing.Platform.csproj                | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/Platform/Microsoft.Testing.Platform/Microsoft.Testing.Platform.csproj b/src/Platform/Microsoft.Testing.Platform/Microsoft.Testing.Platform.csproj
index 3fd6572bc4..2d247d3102 100644
--- a/src/Platform/Microsoft.Testing.Platform/Microsoft.Testing.Platform.csproj
+++ b/src/Platform/Microsoft.Testing.Platform/Microsoft.Testing.Platform.csproj
@@ -63,10 +63,22 @@ This package provides the core platform and the .NET implementation of the proto
     <InternalsVisibleTo Include="Microsoft.Testing.Extensions.VideoRecorder" Key="$(VsPublicKey)" />
     <InternalsVisibleTo Include="Microsoft.Testing.Extensions.VSTestBridge" Key="$(VsPublicKey)" />
     <InternalsVisibleTo Include="Microsoft.Testing.Extensions.VSTestBridge.UnitTests" Key="$(VsPublicKey)" />
+    <!--
+      Microsoft.Testing.Framework / MSTest.Engine are the (now deprecated) source-generation engine assemblies.
+      They were renamed to Microsoft.Testing.Internal.Framework in https://github.com/microsoft/testfx/pull/2615,
+      which dropped these grants. But the previously shipped MSTest.Engine package (assembly name still
+      Microsoft.Testing.Framework, e.g. the 2.0.0-alpha builds referenced by MSTest.SourceGeneration) was compiled
+      against a platform where the grant existed, so its IL calls internals such as
+      Microsoft.Testing.Platform.Helpers.ArgumentGuard.Ensure. Loading that old engine against a newer platform
+      that no longer grants the friend relationship fails with System.MethodAccessException (see issue #9769).
+      Restoring the grant keeps that binary compatibility, mirroring the TestRequestExecutionTimeInfo workaround.
+    -->
+    <InternalsVisibleTo Include="Microsoft.Testing.Framework" Key="$(VsPublicKey)" />
     <InternalsVisibleTo Include="Microsoft.Testing.Platform.Acceptance.IntegrationTests" Key="$(VsPublicKey)" />
     <InternalsVisibleTo Include="Microsoft.Testing.Platform.AI" Key="$(VsPublicKey)" />
     <InternalsVisibleTo Include="Microsoft.Testing.Platform.UnitTests" Key="$(VsPublicKey)" />
     <InternalsVisibleTo Include="Microsoft.Testing.TestInfrastructure" Key="$(VsPublicKey)" />
+    <InternalsVisibleTo Include="MSTest.Engine" Key="$(VsPublicKey)" />
     <InternalsVisibleTo Include="MSTest.TestAdapter" Key="$(VsPublicKey)" />
     <InternalsVisibleTo Include="TestFramework.ForTestingMSTest" Key="$(VsPublicKey)" />
   </ItemGroup>