Split TestContextImplementation into focused partial-class files

[Evangelink]

Fixes #10270.

TestContextImplementation.cs had grown to 988 lines and mixed several unrelated concerns. The class is already partial, so this is a pure file-organization change — no public/internal API change, no behavior change, no import change for callers.

New layout

File	Lines	Responsibility
TestContextImplementation.cs	242	ctor-injected state, constructors, core TestContext overrides (CurrentTestOutcome, DataConnection, DataRow, Context), test-state setters, Dispose, CloneForDataDrivenIteration
TestContextImplementation.Output.cs	112	Write/WriteLine, DisplayMessage, diagnostic messages, SynchronizedStringBuilder accessors, GetAndClear*
TestContextImplementation.Properties.cs	193	property bag (Properties, TryGetPropertyValue, AddProperty, MergeProperties, CaptureLifecycleProperties) and result files
TestContextImplementation.TempDirectory.cs	222	per-test temp directory state, TestTempDirectory property, directory creation
TestContextImplementation.TempDirectoryNaming.cs	117	MAX_PATH budget computation, name source, sanitization
TestContextImplementation.TempDirectoryCleanup.cs	150	cleanup, retention policy, path-containment helpers

Every file is under 300 lines, and this joins the existing TestContextImplementation.{SynchronizedStringBuilder,ScopedTestContextSetter,LiveOutputScope}.cs partials.

Notes

• The three temp-directory partials are guarded in their entirety by #if !WINDOWS_UWP && !WIN_UI, matching the guards that previously wrapped those members inline. This keeps the UWP/WinUI compilation identical and avoids IDE0005 on usings that are only needed inside the guard.
• Fields moved to the partial that owns them (e.g. _propertiesLock/_testResultFiles → Properties.cs, the SynchronizedStringBuilder fields → Output.cs, temp-dir constants/fields → the temp-dir partials). Constants sit next to the logic that uses them.
• Verified mechanically that the split is content-preserving: after normalizing away preprocessor/using/namespace/attribute-free boilerplate, the multiset of code lines across the six files is identical to the original file plus the five new per-file class declarations and doc headers.

Validation

• .\build.cmd — succeeded, 0 warnings, 0 errors (all TFMs including net462, net8.0, net9.0, uap10.0.16299, net8.0-windows10.0.18362.0, net9.0-windows10.0.17763.0).
• MSTestAdapter.PlatformServices.UnitTests (net9.0) — 985/985 passed.
• MSTestAdapter.UnitTests (net9.0) — 56/56 passed.

[Copilot]

Pull request overview

Splits TestContextImplementation into focused partial-class files without changing behavior or APIs.

Changes:

• Separates output, properties, and temporary-directory concerns.
• Preserves conditional compilation and field ownership.
• Keeps every partial file under 300 lines.

Show a summary per file

File	Description
TestContextImplementation.cs	Retains core state and lifecycle logic.
TestContextImplementation.Output.cs	Contains output and diagnostic messaging.
TestContextImplementation.Properties.cs	Contains property and result-file handling.
TestContextImplementation.TempDirectory.cs	Contains temporary-directory creation.
TestContextImplementation.TempDirectoryNaming.cs	Contains naming and sanitization logic.
TestContextImplementation.TempDirectoryCleanup.cs	Contains cleanup and retention logic.

Review details

• Files reviewed: 6/6 changed files
• Comments generated: 0
• Review effort level: Medium

[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

Pure file-organization refactoring — code moved verbatim from TestContextImplementation.cs into five new partial-class files. No behavioral, API, or logic changes detected.

Verdict Table

#	Dimension	Verdict
1	Algorithmic Correctness	✅ N/A — no logic changes
2	Threading & Concurrency	✅ N/A — synchronization code moved intact
3	Security & IPC Contract Safety	✅ N/A
4	Public API & Binary Compatibility	✅ No API surface change
5	Performance & Allocations	✅ N/A
6	Cross-TFM Compatibility	✅ Preprocessor guards preserved correctly (#if !WINDOWS_UWP && !WIN_UI wraps entire temp-directory partials; #if NET9_0_OR_GREATER Lock usage preserved)
7	Error Handling	✅ N/A
8	Logging & Diagnostics	✅ N/A
9	Resource Management	✅ N/A
10	Naming & Conventions	✅ File names follow TypeName.Concern.cs convention
11	Documentation	✅ Each partial has a <summary> doc comment describing its responsibility
12	Code Style	✅ Consistent with codebase
13	Using Directives	✅ Each file has only the usings it needs; removed System.Collections.ObjectModel from main file (moved to Properties.cs)
14	Test Coverage	✅ N/A — no new behavior to test
15	Localization	✅ N/A
16	Backward Compatibility	✅ No breaking changes
17	Scope Discipline	✅ Single concern (file organization)
18	Build Infrastructure	✅ N/A
19	Configuration	✅ N/A
20	Dependencies	✅ N/A
21	Serialization	✅ N/A
22	PowerShell / Scripts	✅ N/A

Notes

• The split is well-motivated: the original 988-line file is now six files each under 300 lines, with clear single-responsibility boundaries (Output, Properties, TempDirectory, TempDirectoryNaming, TempDirectoryCleanup).
• Fields are co-located with the logic that owns them — good practice for partial classes.
• The three temp-directory partials correctly wrap the entire file in #if !WINDOWS_UWP && !WIN_UI, which is cleaner than the inline guards in the original and avoids IDE0005 warnings on platform-specific usings.

No issues found. Clean refactoring.

[github-actions]

🔴 Build Failure Analysis

The build is failing across all legs (Linux, macOS, Windows — both Debug and Release) with the same root cause.

Root Cause

src/Analyzers/MSTest.Analyzers/xlf/Resources.fr.xlf (and likely other .xlf files) is out of date with Resources.resx.

'xlf/Resources.fr.xlf' is out-of-date with 'Resources.resx'.
Project: src/Analyzers/MSTest.Analyzers/MSTest.Analyzers.csproj
Target:  _UpdateXlf

This happens when a new resource string is added to Resources.resx but the localization .xlf files are not regenerated.

Fix

Run the following command locally, then commit the updated .xlf files:

dotnet msbuild src/Analyzers/MSTest.Analyzers/MSTest.Analyzers.csproj /t:UpdateXlf

This will regenerate all files under src/Analyzers/MSTest.Analyzers/xlf/. Commit all modified .xlf files in that directory.

i️ This is documented in the Localization Guidelines: "NEVER manually modify *.xlf files. Instead, regenerate them by running dotnet msbuild <project>.csproj /t:UpdateXlf"

🤖 Automated content by GitHub Copilot. Generated by the Build Failure Analysis workflow. · sonnet46 32.6 AIC · ⌖ 5.28 AIC · ⊞ 8K · [◷]( · ◷)

[Copilot]

Review details

• Files reviewed: 6/6 changed files
• Comments generated: 0 new
• Review effort level: Medium