Extract shared STA-thread dispatch helper (#9303)

[Evangelink]

Fixes #9303. Extracts a shared internal STA-thread dispatch helper for MSTest adapter execution paths while preserving thread names, warning/error handling, apartment state, and async bridging behavior.

[Copilot]

Pull request overview

This PR addresses issue #9303 by extracting the duplicated Windows STA/apartment-thread dispatch pattern into a shared internal helper in MSTestAdapter.PlatformServices, and then routing the existing adapter execution paths through that helper to keep behavior consistent (thread naming, warnings, and async bridging).

Changes:

• Introduces StaThreadHelper to centralize “run on requested apartment state if needed” logic (plus a dedicated STA runner used by TestExecutionManager).
• Refactors TestClassInfo class initialize/cleanup and MSTestExecutor entry-point execution to use the shared helper.
• Simplifies the STA dispatch code path in TestExecutionManager by delegating to StaThreadHelper.RunOnStaThreadAsync.

Show a summary per file

File	Description
src/Adapter/MSTestAdapter.PlatformServices/Helpers/StaThreadHelper.cs	Adds shared helper methods for apartment-thread dispatch and STA-thread execution bridging.
src/Adapter/MSTestAdapter.PlatformServices/Execution/TestExecutionManager.cs	Replaces inline STA thread/TCS block with StaThreadHelper.RunOnStaThreadAsync.
src/Adapter/MSTestAdapter.PlatformServices/Execution/TestClassInfo.Initializer.cs	Routes STATestClass class-initialize execution through RunOnApartmentThreadIfNeededAsync.
src/Adapter/MSTestAdapter.PlatformServices/Execution/TestClassInfo.Cleanup.cs	Routes STATestClass class-cleanup execution through RunOnApartmentThreadIfNeededAsync.
src/Adapter/MSTest.TestAdapter/VSTestAdapter/MSTestExecutor.cs	Uses the shared helper for entry-point apartment dispatch and Windows-only STA warning.

Copilot's findings

• Files reviewed: 5/5 changed files
• Comments generated: 1

[Copilot]

Copilot's findings

• Files reviewed: 5/5 changed files
• Comments generated: 2

[Evangelink]

🔍 Build Failure Analysis

Summary — The build of Microsoft.Testing.Platform.csproj failed because TerminalResources.cs.xlf was out-of-date with TerminalResources.resx: eight new resource strings added to the .resx by a concurrent base-branch PR were not reflected in the XLF on this branch. Microsoft.Testing.Extensions.AzureDevOpsReport.csproj failed as a downstream cascade.

i️ This PR has already been merged. The XLF was fixed on main by PR #9329 (merged at 12:36Z, 1 minute before this PR merged at 12:37Z). main is currently clean.

---

Root cause: Stale XLF — TerminalResources.cs.xlf out-of-date with TerminalResources.resx

PR #9294 ("Add orchestrator TestInProgress/TestDiscovered overloads for SDK parity", merged 2026-06-22T10:24Z) added 8 new resource strings to TerminalResources.resx and regenerated the XLF in the same commit. This PR (#9326) was opened at 09:22Z — before #9294 merged — so when the branch later incorporated the updated base branch (which included the new .resx entries), the XLF on the PR branch was not regenerated to match, leaving it stale.

The _UpdateXlf MSBuild target (from Microsoft.DotNet.XliffTasks) performs a strict in-sync check at CI time and fails the build rather than auto-updating, by design.

Missing trans-unit entries in TerminalResources.cs.xlf (present in .resx, absent in XLF):

Resource key	Value
Try	try {0}
Retried	retried
RunningTestsFrom	Running tests from
DiscoveringTestsFrom	Discovering tests from
Error	error
DiscoveredTestsInAssembly	Discovered {0} tests in assembly
DiscoveredTestsSummarySingular	Discovered {0} tests.
DiscoveredTestsSummary	Discovered {0} tests in {1} assemblies.

Affected errors (3× same message, one per TFM):

• Microsoft.DotNet.XliffTasks.targets:84 — 'OutputDevice/Terminal/xlf/TerminalResources.cs.xlf' is out-of-date with 'OutputDevice/Terminal/TerminalResources.resx'
  • Project: src/Platform/Microsoft.Testing.Platform/Microsoft.Testing.Platform.csproj

Cascading failure:

• src/Platform/Microsoft.Testing.Extensions.AzureDevOpsReport/Microsoft.Testing.Extensions.AzureDevOpsReport.csproj — failed (1.1s) because it depends on Microsoft.Testing.Platform.

Proposed fix (for future PRs in this situation):

After merging or rebasing onto a base branch that updated a .resx file, regenerate all XLF files:

dotnet msbuild src/Platform/Microsoft.Testing.Platform/Microsoft.Testing.Platform.csproj /t:UpdateXlf

Then commit the updated xlf/*.xlf files. Per repo guidelines, never hand-edit XLF files directly.

---

Build overview

Build: FAILED
Duration: 75.3s
MSBuild: 18.7.0-preview
Projects: 46  Errors: 4  Warnings: 0

Failed projects:
  ✗ Build.proj (75.1s)
  ✗ NonWindowsTests.slnf (47.7s)
  ✗ Microsoft.Testing.Extensions.AzureDevOpsReport.csproj (1.1s)

All MSBuild errors (4)

Code	Project	File	Message
(XliffTasks)	Microsoft.Testing.Platform.csproj	Microsoft.DotNet.XliffTasks.targets:84	'OutputDevice/Terminal/xlf/TerminalResources.cs.xlf' is out-of-date with 'OutputDevice/Terminal/TerminalResources.resx'
(XliffTasks)	Microsoft.Testing.Platform.csproj	Microsoft.DotNet.XliffTasks.targets:84	(same, 2nd TFM)
(XliffTasks)	Microsoft.Testing.Platform.csproj	Microsoft.DotNet.XliffTasks.targets:84	(same, 3rd TFM)
—	—	—	Build failed.

---

_{🤖 Generated by the Build Failure Analysis workflow using [binlog-mcp]((dev.azure.com/redacted) · commit cef92d8}

🤖 Automated content by GitHub Copilot. Posted via a maintainer's GitHub token, so it appears under their account — the account owner did not write or approve this content personally. Generated by the Build Failure Analysis workflow. · 560 AIC · ⌖ 22.4 AIC · ⊞ 46.9K · [◷]( · ◷)