Refactor fixture signature code fixers to shared base class

[Copilot]

Six fixture-method code fixers in MSTest.Analyzers.CodeFixes had near-identical implementations, differing only by diagnostic ID and signature flags. This change centralizes shared behavior to remove lock-step duplication and reduce maintenance risk.

• What changed

  • Added FixtureMethodSignatureFixerBase in src/Analyzers/MSTest.Analyzers.CodeFixes/Helpers/.
  • Moved common code-fix flow into the base:
    • FixableDiagnosticIds
    • GetFixAllProvider()
    • RegisterCodeFixesAsync(...)
  • Kept per-rule variability as abstract members:
    • DiagnosticRuleId
    • IsParameterLess
    • ShouldBeStatic

• Refactored fixers

  • Updated these concrete providers to inherit from the base and only declare rule-specific values:
    • AssemblyCleanupShouldBeValidFixer
    • AssemblyInitializeShouldBeValidFixer
    • ClassCleanupShouldBeValidFixer
    • ClassInitializeShouldBeValidFixer
    • TestCleanupShouldBeValidFixer
    • TestInitializeShouldBeValidFixer

• MEF/export behavior

  • Preserved [ExportCodeFixProvider(...)] and [Shared] on each concrete fixer type.

[ExportCodeFixProvider(LanguageNames.CSharp, Name = nameof(TestCleanupShouldBeValidFixer))]
[Shared]
public sealed class TestCleanupShouldBeValidFixer : FixtureMethodSignatureFixerBase
{
    protected override string DiagnosticRuleId => DiagnosticIds.TestCleanupShouldBeValidRuleId;
    protected override bool IsParameterLess => true;
    protected override bool ShouldBeStatic => false;
}

[Copilot]

Pull request overview

This PR refactors the MSTest fixture-method signature code fix providers in MSTest.Analyzers.CodeFixes by extracting the shared “fix signature” code-fix workflow into a new base class, reducing duplication across the six near-identical fixers.

Changes:

• Added FixtureMethodSignatureFixerBase to centralize FixableDiagnosticIds, GetFixAllProvider(), and RegisterCodeFixesAsync(...).
• Updated the six fixture signature fixers to inherit from the base class and provide only rule-specific configuration (DiagnosticRuleId, IsParameterLess, ShouldBeStatic).
• Preserved MEF export behavior ([ExportCodeFixProvider] and [Shared]) on each concrete fixer type.

Show a summary per file

File	Description
src/Analyzers/MSTest.Analyzers.CodeFixes/Helpers/FixtureMethodSignatureFixerBase.cs	New shared base implementing the common code-fix registration and “fix signature” action creation.
src/Analyzers/MSTest.Analyzers.CodeFixes/TestInitializeShouldBeValidFixer.cs	Refactored to inherit from the shared base and provide rule-specific flags.
src/Analyzers/MSTest.Analyzers.CodeFixes/TestCleanupShouldBeValidFixer.cs	Refactored to inherit from the shared base and provide rule-specific flags.
src/Analyzers/MSTest.Analyzers.CodeFixes/ClassInitializeShouldBeValidFixer.cs	Refactored to inherit from the shared base and provide rule-specific flags.
src/Analyzers/MSTest.Analyzers.CodeFixes/ClassCleanupShouldBeValidFixer.cs	Refactored to inherit from the shared base and provide rule-specific flags.
src/Analyzers/MSTest.Analyzers.CodeFixes/AssemblyInitializeShouldBeValidFixer.cs	Refactored to inherit from the shared base and provide rule-specific flags.
src/Analyzers/MSTest.Analyzers.CodeFixes/AssemblyCleanupShouldBeValidFixer.cs	Refactored to inherit from the shared base and provide rule-specific flags.

Copilot's findings

• Files reviewed: 7/7 changed files
• Comments generated: 1

[Copilot]

Copilot's findings

• Files reviewed: 7/7 changed files
• Comments generated: 0 new