Implementation completed for JsonDocument.Parse().RootElement analyzer:

• Create analyzer to detect JsonDocument.Parse().RootElement pattern without disposal (CA2026)
• Create code fixer to replace with JsonElement.Parse()
• Add resource strings for diagnostic messages
• Create comprehensive unit tests for analyzer
• Create comprehensive unit tests for code fixer
• Build and test implementation
• Run dotnet format
• Request code review (passed with no issues)
• Regenerate auto-generated documentation files
• Address code review feedback (round 1)
• Address code review feedback (round 2)
• Address code review feedback (round 3)
• Convert tests to raw string literals

Summary

Successfully implemented CA2026 analyzer and code fixer for detecting JsonDocument.Parse().RootElement patterns without disposal. The analyzer helps developers avoid resource leaks by suggesting the use of JsonElement.Parse() instead.

Key features:

• Detects immediate RootElement access after JsonDocument.Parse()
• Only suggests fix when JsonElement.Parse has matching overload with same parameter types
• Automatic code fix replaces entire pattern with JsonElement.Parse()
• 13 comprehensive unit tests all passing (8 original + 5 new corner cases)
• Uses WellKnownTypeNames and optimized loops for performance
• Consolidated validation logic for cleaner code
• Tests use modern raw string literals for better readability

Test coverage includes:

• Basic positive and negative cases
• Proper disposal detection (using statements/declarations)
• Mismatched overloads (no diagnostic when JsonElement.Parse doesn't have matching signature)
• Chained property access
• Variable storage pattern
• Lambda expressions
• Multiple parameter overloads

Files changed:

• Analyzer: PreferJsonElementParse.cs
• Fixer: PreferJsonElementParse.Fixer.cs
• Tests: PreferJsonElementParseTests.cs
• Resources: MicrosoftNetCoreAnalyzersResources.resx
• Config: DiagnosticCategoryAndIdRanges.txt, AnalyzerReleases.Unshipped.md, WellKnownTypeNames.cs
• Auto-generated docs: Microsoft.CodeAnalysis.NetAnalyzers.md, Microsoft.CodeAnalysis.NetAnalyzers.sarif

This pull request was created as a result of the following prompt from Copilot chat.

Implement a new Roslyn analyzer and associated code fixer in the dotnet/sdk repo (netanalyzers) to address dotnet/runtime#111957. The analyzer should flag common patterns where developers obtain a JsonElement by accessing JsonDocument.Parse("json").RootElement without disposing the JsonDocument, e.g.:

JsonElement element = JsonDocument.Parse("json").RootElement;

The analyzer should recommend switching to the new JsonElement.Parse methods approved in dotnet/runtime#108930 for .NET 10. The code fixer should automatically replace the flagged patterns with calls to JsonElement.Parse, improving code correctness and resource management.

Include:

• Analyzer code to detect patterns described in the issue.
• Code fixer for automatic replacement.
• Unit tests for both analyzer and fixer.
• Documentation updates if necessary.

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.