Cover the fixture-scope branches of MSTEST0075

[Amaury Levé (Evangelink)]

Closes #10349
Closes #10369

(#10349 and #10369 are duplicates of each other — the test-improver workflow filed the same gap twice.)

What this covers

CurrentDirectoryMutationUnderParallelizationAnalyzer decides, per enclosing method, whether to report a current-directory mutation and — if so — where AddResourceLockFixer may place [ResourceLock]. That yields three distinct outcomes, and this file covered none of them: every pre-existing test here pins the plain test-method case.

New test	Enclosing method	Outcome
WhenTestInitializeSetsCurrentDirectoryViaDirectory_Diagnostic	[TestInitialize]	Reported; fix placed on the class
WhenAssemblyInitializeSetsCurrentDirectoryViaDirectory_NoDiagnostic	[AssemblyInitialize]	Silent
WhenGlobalTestInitializeSetsCurrentDirectoryViaDirectory_DiagnosticWithoutFix	[GlobalTestInitialize]	Reported; no fix offered

Notes on each:

• [TestInitialize] is a class-scoped fixture, so a [ResourceLock] on the fixture method itself would be ignored — discovery reads locks only from the test class and the test method. The test asserts the fixer's class-scope placement, which is the first class-scope fix assertion in this file. (The sibling CultureMutationUnderParallelizationAnalyzerTests only calls VerifyAnalyzerAsync, so it cannot pin this at all.)
• [AssemblyInitialize] is serialized ahead of every worker, so it cannot race a concurrent test — flagging it would be a false positive.
• [GlobalTestInitialize] genuinely races, but a global fixture has no effective lock target: the enclosing class is not one, because locking it would serialize only that class's tests while the fixture kept racing the tests of every other class. So the analyzer reports without offering a fix. This third branch had no coverage in any of the three parallel-safety analyzer test files.

Mutation-verified

These are not decorative — each was checked by breaking the analyzer and confirming exactly one test caught it, with no pre-existing test in the repo noticing:

Injected regression	Result
Add AssemblyInitializeAttribute to GetFixtureAttributeSymbols	only the [AssemblyInitialize] test fails
Add GlobalTestInitializeAttribute to GetClassScopedFixtureAttributeSymbols	only the [GlobalTestInitialize] test fails

The second is the interesting one: that regression would make the fixer emit a class-level [ResourceLock] that does nothing at run time, and before this PR nothing would have caught it.

Validation

Full MSTest.Analyzers.UnitTests suite: net8.0 1688/1688, net472 1632/1632. Build clean, 0 warnings. No production code changed.

---

The MSTEST0081 half of this backlog is split out into #10386, since it covers a different analyzer and issue.

[Copilot]

Pull request overview

Adds analyzer edge-case coverage for MSTEST0075 and MSTEST0081 without changing production code.

Changes:

• Tests fixture-method handling and code-fix placement for current-directory mutations.
• Tests duplicate generic and non-generic filter-provider registrations, including CS0579 behavior.

Show a summary per file

File	Description
CurrentDirectoryMutationUnderParallelizationAnalyzerTests.cs	Covers test and assembly initialization scenarios.
TestFilterProviderShouldBeValidAnalyzerTests.cs	Covers same-shape duplicate provider registrations.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Balanced

[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.

Summary

This PR adds well-crafted edge-case tests for two analyzers (MSTEST0075 and MSTEST0081), closing three backlog items. No production code is changed.

Review

✅ No issues found. This is a clean, test-only PR that strengthens analyzer coverage.

Highlights

Dimension	Assessment
Correctness	✅ Tests correctly exercise the fixture hierarchy ([TestInitialize] → diagnostic, [AssemblyInitialize] → no diagnostic) and the AllowMultiple = false CS0579 interaction
Completeness	✅ Code fix assertion included for the diagnostic case; both TFMs validated; #if NET guard correctly scopes the generic-attribute test
Naming & readability	✅ Method names follow the When..._Outcome convention; inline comments explain why each expectation holds
Test quality	✅ No flakiness vectors; assertions are specific (rule + location + arguments); no over-assertion
Style	✅ Consistent with sibling test files; no trailing whitespace; file ends with newline
Public API	✅ N/A — no production changes
Security	✅ N/A

Minor observation (non-blocking)

The "/tmp" literal in the test snippets is fine for Roslyn in-memory compilation (no real I/O), but if future tests ever execute these snippets end-to-end, a platform-neutral path would be safer. Not actionable here.

Verdict: No changes requested. Ship it. 🚀

[Copilot]

Review details

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

[github-actions]

🧪 Test quality grade — PR #10383

Grade	Test	Mutation	Notes	How to improve
A (90–100)	new CurrentDirectoryMutationUnderParallelizationAnalyzerTests. WhenTestInitializeSetsCurrentDirectoryViaDirectory_ Diagnostic	4/4 killed	VerifyCodeFixAsync checks diagnostic location, argument, and full code transformation to class-level ResourceLock.	—
A (90–100)	new CurrentDirectoryMutationUnderParallelizationAnalyzerTests. WhenAssemblyInitializeSetsCurrentDirectoryViaDirectory_ NoDiagnostic	3/3 killed	Negative test with clear rationale; VerifyCodeFixAsync(code, code) asserts no diagnostic and no code change.	—
A (90–100)	new CurrentDirectoryMutationUnderParallelizationAnalyzerTests. WhenGlobalTestInitializeSetsCurrentDirectoryViaDirectory_ DiagnosticWithoutFix	3/3 killed	Pins the third branch (report, no fix); third VerifyCodeFixAsync arg == code asserts fixer is intentionally absent.	—

_{This advisory comment was generated automatically. Grades are heuristic and informational — they do not block merging. Re-run with /grade-tests.}

🤖 Automated content by GitHub Copilot. Generated by the Grade Tests on PR (on open / sync) workflow. · sonnet46 51.9 AIC · ⌖ 6.84 AIC · ⊞ 11.8K · [◷]( · ◷)