refactor: Consolidate duplicated generator logic into GeneratorUtils

[thomhurst]

Summary

• Moved shared code generation logic from 4 generator files to GeneratorUtils.cs
• Added 4 new utility methods: GenerateCliAttributeString(), GenerateValidationAttributes(), GenerateXmlDocumentation(), GenerateMethodNameFromCommandParts(), and GenerateMethodNameFromLastCommandPart()
• Reduced ~80 lines of duplicated code across OptionsClassGenerator.cs, GlobalOptionsBaseGenerator.cs, ServiceInterfaceGenerator.cs, ServiceImplementationGenerator.cs, and SubDomainClassGenerator.cs

Details

The following duplicated logic has been consolidated:

Method	Description	Previously Duplicated In
GenerateCliAttributeString()	Generates CliFlag/CliOption attribute strings	OptionsClassGenerator, GlobalOptionsBaseGenerator
GenerateValidationAttributes()	Generates Range/RegularExpression attributes	OptionsClassGenerator, GlobalOptionsBaseGenerator
GenerateXmlDocumentation()	Generates XML summary blocks	All 5 generator files
GenerateMethodNameFromCommandParts()	Converts command parts to PascalCase method name	ServiceInterfaceGenerator, ServiceImplementationGenerator
GenerateMethodNameFromLastCommandPart()	Generates method name from last command segment	SubDomainClassGenerator

Fixes #1456

Test plan

• Build succeeds: dotnet build tools/ModularPipelines.OptionsGenerator
• All existing tests pass
• Generated code output is identical (no behavioral changes)

🤖 Generated with Claude Code

[github-actions]

Summary

Consolidates ~80 lines of duplicated generator code into shared utility methods in GeneratorUtils.cs.

Critical Issues

None found ✅

Suggestions

1. Minor case handling inconsistency in GenerateMethodNameFromCommandParts (GeneratorUtils.cs:207)

The new shared method uses .ToLowerInvariant() for the rest of the string with a length check:

.Select(p => char.ToUpperInvariant(p[0]) + (p.Length > 1 ? p[1..].ToLowerInvariant() : ""))

But the original implementation in ServiceImplementationGenerator.cs used:

.Select(p => char.ToUpperInvariant(p[0]) + p[1..].ToLowerInvariant())

The new version adds a length check which is safer and prevents potential index out of bounds if a part is a single character. This is actually an improvement, but means the generated code output may differ in edge cases with single-character command parts. Verify this doesn't break existing generated output.

2. Consider adding unit tests for the new utility methods

The PR consolidates critical code generation logic. Adding unit tests for these methods would:

• Prevent future regressions
• Document expected behavior with examples
• Verify edge cases (empty strings, special characters, single-character parts)

Example test cases:

• GenerateMethodNameFromCommandParts(["build", "server"]) should return "BuildServer"
• GenerateMethodNameFromCommandParts(["a", "b-c"]) should return "ABC"
• GenerateMethodNameFromLastCommandPart(...) with various inputs

Verdict

✅ APPROVE - Well-executed refactoring with proper DRY principles. The code consolidation is sound and maintains the original behavior (with one minor safety improvement noted above).