Restore InternalsVisibleTo for deprecated MSTest.Engine to fix MethodAccessException (#9769)

[Evangelink]

Problem

Native AOT / source-gen test projects fail at runtime with:

System.MethodAccessException: Attempt by method
'Microsoft.Testing.Framework.TestApplicationBuilderExtensions.AddTestFramework(...)'
to access method 'Microsoft.Testing.Platform.Helpers.ArgumentGuard.Ensure(Boolean, String, String)' failed.

Reported in #9769 (comment). Zero tests run, exit code 134.

Root cause

MSTest.Sdk source-gen mode pulls in the (now deprecated) MSTest.Engine package, whose assembly name is still Microsoft.Testing.Framework. That assembly's TestApplicationBuilderExtensions.AddTestFramework calls the internal Microsoft.Testing.Platform.Helpers.ArgumentGuard.Ensure.

The InternalsVisibleTo grants for Microsoft.Testing.Framework / MSTest.Engine were removed in #2615 when those projects were renamed to Microsoft.Testing.Internal.Framework. The already-shipped engine binary was compiled while the grant existed, so loading it against a newer Microsoft.Testing.Platform that no longer grants the friend relationship throws MethodAccessException.

Fix

Restore the two InternalsVisibleTo grants (Microsoft.Testing.Framework, MSTest.Engine) in Microsoft.Testing.Platform.csproj, with a comment explaining the binary-compatibility rationale. This mirrors the existing TestRequestExecutionTimeInfo compatibility workaround (issue #8925). A single keyed grant re-enables every internal the old engine reaches, not just ArgumentGuard.

Verification

• Targeted build of Microsoft.Testing.Platform succeeds (0 warnings, 0 errors) across net8.0/net9.0/netstandard2.0.
• Confirmed the emitted InternalsVisibleTo attributes carry the correct MSFT strong-name public key, matching how the shipped engine is signed, so the keyed grant matches at load time.

Fixes #9769

[Copilot]

Pull request overview

Restores InternalsVisibleTo grants in Microsoft.Testing.Platform to preserve runtime binary compatibility with the already-shipped (deprecated) MSTest.Engine / Microsoft.Testing.Framework assemblies that were compiled when those friend-assembly relationships existed, preventing System.MethodAccessException in Native AOT / source-gen scenarios.

Changes:

• Re-add InternalsVisibleTo for Microsoft.Testing.Framework (engine assembly name) using the strong-name key.
• Re-add InternalsVisibleTo for MSTest.Engine using the strong-name key.
• Document the binary-compatibility rationale inline in the .csproj.

Show a summary per file

File	Description
src/Platform/Microsoft.Testing.Platform/Microsoft.Testing.Platform.csproj	Restores friend-assembly access for deprecated engine assemblies to avoid runtime MethodAccessException with older shipped binaries.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Low

[github-actions]

Note

🤖 Automated review by GitHub Copilot. Generated by the Expert Code Review workflow. To request a follow-up action, reply by tagging @copilot directly.

Review Summary

This PR restores InternalsVisibleTo grants for the deprecated Microsoft.Testing.Framework and MSTest.Engine assemblies to fix a MethodAccessException when older pre-compiled engine binaries call internal APIs on a newer platform (issue #9769).

Verdict Table

#	Dimension	Verdict
1	Algorithmic Correctness	✅ N/A — no logic changes
2	Performance	✅ N/A — no runtime impact
3	Thread Safety	✅ N/A
4	Resource Management	✅ N/A
5	Error Handling	✅ N/A
6	Security	✅ OK — grants are to strong-named assemblies with a known key
7	API Design	✅ OK — no new public API surface
8	Backward Compatibility	✅ OK — this is explicitly a backward-compat fix
9	Cross-TFM	✅ N/A
10	Naming & Style	✅ OK — alphabetical order maintained
11	Documentation	✅ OK — thorough inline comment explains rationale and links issue
12	Localization	✅ N/A
13	Testing	✅ N/A — the fix is validated by absence of MethodAccessException at runtime
14	Logging & Diagnostics	✅ N/A
15	IPC & Serialization	✅ N/A
16	Configuration	✅ N/A
17	Build & Packaging	✅ OK
18	Extensibility	✅ N/A
19	Scope Discipline	✅ OK — single-concern PR
20	Code Duplication	✅ N/A
21	Nullability	✅ N/A
22	Disposal	✅ N/A

Summary

Clean PR. The change is minimal, well-documented with an inline comment explaining the binary-compat scenario, references the originating issue (#9769) and the historical PR (#2615), and maintains alphabetical ordering of the InternalsVisibleTo entries. No issues found.