[test-improver] test: add DataTestMethod edge cases for TypeContainingTestMethodShouldBeATestClassAnalyzer (MSTEST0030)

[Evangelink]

Goal and Rationale

TypeContainingTestMethodShouldBeATestClassAnalyzer (MSTEST0030) flags non-test classes that contain test methods (direct or inherited). The analyzer detects test methods via attribute.AttributeClass.Inherits(testMethodAttributeSymbol), which should recognize DataTestMethodAttribute since it inherits from TestMethodAttribute. Two concrete scenarios were not explicitly tested:

1. DataTestMethod directly on a method in a non-test class — the Inherits() check should recognize DataTestMethodAttribute as a test method, triggering the diagnostic.

2. DataTestMethod inherited from an abstract base class — the inheritance walk (while (currentType is not null)) should traverse up to the abstract base and detect the DataTestMethod. The abstract base is exempt (per the IsAbstract guard), but the concrete derived class should fire the diagnostic.

Approach

Added two new [TestMethod] test cases to TypeContainingTestMethodShouldBeATestClassAnalyzerTests.cs:

• WhenNonTestClassHasDataTestMethod_Diagnostic — confirms [DataTestMethod] (first-party TestMethodAttribute subclass) triggers the diagnostic and the code fix correctly adds [TestClass]
• WhenNonTestClassInheritsDataTestMethodFromAbstractBase_Diagnostic — confirms the inheritance walk detects [DataTestMethod] from an abstract base, firing only on the concrete derived class (abstract base is exempt)

Test Status

Test run summary: Passed!
  total: 16
  failed: 0
  succeeded: 16
  skipped: 0
  duration: 7s 373ms

✅ All 16 tests pass (MSTest.Analyzers.UnitTests, net8.0, Debug — 14 original + 2 new).

Reproducibility

./build.sh --restore   # first run only
.dotnet/dotnet test test/UnitTests/MSTest.Analyzers.UnitTests/MSTest.Analyzers.UnitTests.csproj \
  -f net8.0 --no-build -c Debug \
  --filter "ClassName=MSTest.Analyzers.Test.TypeContainingTestMethodShouldBeATestClassAnalyzerTests"

Trade-offs

• Tests exercise existing code paths only — no production changes, no maintenance burden beyond the tests.
• Both tests document how the Inherits() check handles DataTestMethodAttribute (the built-in TestMethodAttribute subclass), complementing the existing test for custom subclasses.

🤖 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 Test Improver workflow. · 1K AIC · ⌖ 23 AIC · [◷]( · ◷)

Add this agentic workflows to your repo

To install this agentic workflow, run

gh aw add githubnext/agentics/workflows/test-improver.md@main

[Copilot]

Pull request overview

Adds regression/edge-case coverage to the MSTest analyzer test suite for MSTEST0030 (TypeContainingTestMethodShouldBeATestClassAnalyzer), specifically ensuring that [DataTestMethod] is treated as a test method (via inheritance from TestMethodAttribute) both when applied directly and when inherited from an abstract base type.

Changes:

• Add a new code-fix test verifying a diagnostic is produced when a non-test class contains a [DataTestMethod].
• Add a new code-fix test verifying the analyzer’s base-type walk detects a [DataTestMethod] declared on an abstract base type and reports only on the concrete derived non-test class.

Show a summary per file

File	Description
test/UnitTests/MSTest.Analyzers.UnitTests/TypeContainingTestMethodShouldBeATestClassAnalyzerTests.cs	Adds two new analyzer/code-fix test cases covering [DataTestMethod] direct usage and inherited-from-abstract-base scenarios for MSTEST0030.

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 0