Unify IndentedStringBuilder across MSTest source generators

[Evangelink]

Fixes #8987

Summary

• Kept src/Analyzers/MSTest.SourceGeneration/Helpers/IndentedStringBuilder.cs as the canonical helper.
• Linked the canonical helper (and its deterministic Constants.NewLine dependency) into MSTest.AotReflection.SourceGeneration.
• Removed the AotReflection-specific duplicate helper while preserving its fluent Append/AppendLine and Block style.

Validation

• dotnet build src\Analyzers\MSTest.SourceGeneration\MSTest.SourceGeneration.csproj -v minimal -m:1 -bl:{}
• dotnet build src\Analyzers\MSTest.AotReflection.SourceGeneration\MSTest.AotReflection.SourceGeneration.csproj -v minimal -m:1 -bl:{}
• dotnet build src\Analyzers\MSTest.Analyzers\MSTest.Analyzers.csproj -v minimal -m:1 -bl:{}
• dotnet test --project test\UnitTests\MSTest.SourceGeneration.UnitTests\MSTest.SourceGeneration.UnitTests.csproj --framework net8.0 --no-build -p:UsingDotNetTest=true -bl:{}
• dotnet test --project test\UnitTests\MSTest.AotReflection.SourceGeneration.UnitTests\MSTest.AotReflection.SourceGeneration.UnitTests.csproj --framework net8.0 --no-build -p:UsingDotNetTest=true -bl:{}
• dotnet test --project test\UnitTests\MSTest.Analyzers.UnitTests\MSTest.Analyzers.UnitTests.csproj --framework net8.0 --no-build -p:UsingDotNetTest=true -bl:{}

[Copilot]

Pull request overview

This PR removes the duplicated IndentedStringBuilder implementation from MSTest.AotReflection.SourceGeneration by reusing the canonical helper from MSTest.SourceGeneration (via linked Compile items), ensuring both generators share the same indentation/block API and deterministic newline behavior.

Changes:

• Updated the canonical IndentedStringBuilder to support the fluent API shape and Block(...) pattern used by the AOT reflection generator.
• Linked IndentedStringBuilder.cs and its Constants.NewLine dependency into MSTest.AotReflection.SourceGeneration.
• Deleted the AOT reflection project’s duplicate helper and updated generator code to use the canonical helper’s namespace.

Show a summary per file

File	Description
src/Analyzers/MSTest.SourceGeneration/Helpers/IndentedStringBuilder.cs	Makes the canonical helper fluent and adds Block(...) to match both generators’ call patterns while keeping deterministic newlines.
src/Analyzers/MSTest.AotReflection.SourceGeneration/MSTest.AotReflection.SourceGeneration.csproj	Links the canonical helper (and Constants.cs) into the AOT reflection generator project.
src/Analyzers/MSTest.AotReflection.SourceGeneration/Helpers/IndentedStringBuilder.cs	Removes the duplicate, AOT-specific helper implementation.
src/Analyzers/MSTest.AotReflection.SourceGeneration/Generators/MetadataRegistryEmitter.cs	Switches the generator to import the canonical helper namespace.

Copilot's findings

• Files reviewed: 4/4 changed files
• Comments generated: 0

[Evangelink]

Note

🤖 Automated review 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 Expert Code Review workflow. To request a follow-up action, reply by tagging @copilot directly.

#	Dimension	Verdict
15	Code Structure	🔵 1 NIT
16	Naming & Conventions	🔵 1 NIT

✅ 20/22 applicable dimensions clean (12 dimensions N/A for this change set).

• AppendBlock is dead code with no callers — only Block is used. Two internal entry-points for the same operation is mildly confusing. (See inline comment.)

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Overall assessment: The unification is well-executed. The file-linking approach (.csproj <Compile Link="..."/>) is the right mechanism, and switching from platform-specific StringBuilder.AppendLine() to the deterministic Constants.NewLine ("\n") is a genuine improvement for reproducible generator output. All behavioral semantics of the deleted AotReflection-specific IndentedStringBuilder are correctly preserved in the canonical version. The return-type promotion to IndentedStringBuilder (fluent style) is source-compatible with all existing void-discard call sites.

🤖 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 Expert Code Review (on PR ready) workflow. · 716.9 AIC · ⌖ 12.3 AIC · ◷