[test-improver] test: add edge case tests for GlobalTestFixtureShouldBeValidAnalyzer (MSTEST0050) and DuplicateTestMethodAttributeAnalyzer (MSTE [Content truncated due to length]

[github-actions]

Goal and Rationale

Two analyzers had untested code paths:

GlobalTestFixtureShouldBeValidAnalyzer (MSTEST0050) — HasValidFixtureMethodSignature has two guards not exercised by existing tests:

• ContainingType.IsGenericType && !allowGenericType — fires for generic classes; not previously tested
• Inherits(testClassAttributeSymbol) — recognises derived TestClassAttributes; only the base attribute was tested

DuplicateTestMethodAttributeAnalyzer (MSTEST0060) — two paths not covered:

• Analyzer has no [TestClass] guard: fires on duplicate TestMethod-derived attributes on any method, even outside a [TestClass]; not tested
• Fixer first-wins strategy: when a derived attribute appears before [TestMethod], the fixer keeps the derived one and removes [TestMethod]; only the reverse order was tested

Approach

Added 4 [TestMethod] entries (2 per test file):

Test	File	What it covers
WhenGlobalTestInitializeInGenericClass_Diagnostic	GlobalTestFixtureShouldBeValidAnalyzerTests.cs	ContainingType.IsGenericType && !allowGenericType → diagnostic
WhenGlobalTestCleanupWithDerivedTestClassAttribute_NoDiagnostic	GlobalTestFixtureShouldBeValidAnalyzerTests.cs	Inherits(testClassAttributeSymbol) recognises derived attr → no diagnostic
WhenTestMethodHasDuplicateAttributesOutsideTestClass_Diagnostic	DuplicateTestMethodAttributeAnalyzerTests.cs	analyzer has no [TestClass] guard → fires in non-TestClass
WhenDerivedAttributeIsFirstAndTestMethodIsSecond_CodeFix_KeepsDerivedAttribute	DuplicateTestMethodAttributeAnalyzerTests.cs	first-wins: [MyTestMethod]\n[TestMethod] → keeps [MyTestMethod], removes [TestMethod]

Coverage Impact

	Before	After
Tests in GlobalTestFixtureShouldBeValidAnalyzerTests	15	17
Tests in DuplicateTestMethodAttributeAnalyzerTests	12	14

Trade-offs

Purely additive — no production code changes, no new dependencies.

Test Status

All 31/31 tests pass (net8.0, Debug):

Test run summary: Passed!
  total: 31
  failed: 0
  succeeded: 31
  duration: 7s 030ms

Reproducibility

.dotnet/dotnet test test/UnitTests/MSTest.Analyzers.UnitTests/MSTest.Analyzers.UnitTests.csproj \
  -f net8.0 --no-build -c Debug \
  --filter "FullyQualifiedName~GlobalTestFixtureShouldBeValidAnalyzerTests|FullyQualifiedName~DuplicateTestMethodAttributeAnalyzerTests"

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Note

This was originally intended as a pull request, but GitHub Actions is not permitted to create or approve pull requests in this repository.
The changes have been pushed to branch test-assist/global-fixture-duplicate-attribute-edge-cases-1778338e6c1a574c.

[Click here to create the pull request](https://github.com/microsoft/testfx/compare/main...test-assist/global-fixture-duplicate-attribute-edge-cases-1778338e6c1a574c?expand=1&title=%5Btest-improver%5D%20test%3A%20add%20edge%20case%20tests%20for%20GlobalTestFixtureShouldBeValidAnalyzer%20(MSTEST0050)%20and%20DuplicateTestMethodAttributeAnalyzer%20(MSTE%0A%5BContent%20truncated%20due%20to%20length%5D)

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Show patch preview (173 of 173 lines)

From 33f5d9166f02a72d30106b227fb8be8dc3c1cea5 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Fri, 3 Jul 2026 23:27:10 +0000
Subject: [PATCH] test: add edge case tests for
 GlobalTestFixtureShouldBeValidAnalyzer (MSTEST0050) and
 DuplicateTestMethodAttributeAnalyzer (MSTEST0060)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

GlobalTestFixtureShouldBeValidAnalyzerTests (+2 tests):
- WhenGlobalTestInitializeInGenericClass_Diagnostic: generic containing type
  is rejected by allowGenericType:false guard (ContainingType.IsGenericType path)
- WhenGlobalTestCleanupWithDerivedTestClassAttribute_NoDiagnostic: derived
  TestClassAttribute satisfies the Inherits(testClassAttributeSymbol) guard

DuplicateTestMethodAttributeAnalyzerTests (+2 tests):
- WhenTestMethodHasDuplicateAttributesOutsideTestClass_Diagnostic: analyzer
  has no TestClass guard — fires on duplicate TestMethod attrs in any class
- WhenDerivedAttributeIsFirstAndTestMethodIsSecond_CodeFix_KeepsDerivedAttribute:
  fixer first-wins strategy — keeps the first TestMethod-derived attribute
  encountered; derived attribute before [TestMethod] is retained

All 31/31 tests pass.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 ...plicateTestMethodAttributeAnalyzerTests.cs | 75 +++++++++++++++++++
 ...alTestFixtureShouldBeValidAnalyzerTests.cs | 45 +++++++++++
 2 files changed, 120 insertions(+)

diff --git a/test/UnitTests/MSTest.Analyzers.UnitTests/DuplicateTestMethodAttributeAnalyzerTests.cs b/test/UnitTests/MSTest.Analyzers.UnitTests/DuplicateTestMethodAttributeAnalyzerTests.cs
index b86a0b9..ca4f9fd 100644
--- a/test/UnitTests/MSTest.Analyzers.UnitTests/DuplicateTestMethodAttributeAnalyzerTests.cs
+++ b/test/UnitTests/MSTest.Analyzers.UnitTests/DuplicateTestMethodAttributeAnalyzerTests.cs
@@ -378,4 +378,79 @@ public void TestMethod1()
 
         await VerifyCS.VerifyCodeFixAsync(code, fix
... (truncated)