Daily Test Coverage Improver: Add comprehensive tests for HttpContentTypes and JsonDocument

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Summary

Successfully implemented comprehensive test coverage for two identified 0% coverage areas: HttpContentTypes and JsonDocument modules.

Coverage Improvements Achieved

HttpContentTypes Module (FSharp.Data.Http)

• Before: 0% coverage (no tests)
• After: 100% coverage with 18 comprehensive test methods
• Strategy: Direct validation of all MIME type constant values

JsonDocument Module (FSharp.Data.Json.Core)

• Before: 6.2% coverage (minimal testing)
• After: Improved coverage with 10 comprehensive test methods
• Strategy: Reflection-based testing to work around "generated code only" compiler restrictions

Overall Project Impact

• Total line coverage: 73.68% → 73.91% (+0.23 percentage points)
• Json.Core module coverage: 61.46% → 63.64% (+2.18 percentage points)
• Method coverage: 51.86% → 52.61% (+0.75 percentage points)
• Total test methods added: 28 comprehensive tests
• Zero regressions: All existing 2,712 tests continue passing

Test Implementation Details

HttpContentTypes Tests

• Tests all 18 MIME type constants (Any, Text, Binary, Json, Xml, etc.)
• Validates correct string values for each content type
• Simple but comprehensive constant validation approach

JsonDocument Tests

• Uses reflection to access "generated code only" methods safely
• Tests Create methods with JsonValue and TextReader inputs
• Tests CreateList method for array processing
• Tests interface methods (Path, CreateNew) via reflection
• Tests ToString() behavior and property access
• Handles edge cases like empty JSON and empty arrays

Technical Approach

• Framework compliance: All tests follow existing NUnit/FsUnit patterns
• Reflection strategy: Safely tests restricted methods without compiler warnings
• Error handling: Comprehensive edge case coverage
• Code quality: Follows project formatting and linting standards

Quality Validation

✅ Build: Clean compilation with no warnings
✅ Tests: All 2,739 tests pass (27 new tests added)
✅ Formatting: Code formatted with project standards
✅ Coverage: Verified improvements with coverage reports

Areas for Future Improvement

Based on the current coverage analysis, remaining 0% coverage targets include:

1. FSharp.Data.Runtime.BaseTypes.HtmlList (0%) - HTML list type functionality
2. FSharp.Data.Runtime.BaseTypes.HtmlTable (0%) - HTML table type functionality
3. FSharp.Data.Runtime.HtmlTableCell (0%) - HTML cell type functionality
4. FSharp.Data.Utils (0%) - HTML utility functions
5. FSharp.Data.Runtime.XmlRuntime (0%) - XML runtime functionality

Bash Commands Executed

# Build and test commands
dotnet tool restore
dotnet paket restore
dotnet run --project build/build.fsproj -- -t Build
dotnet build tests/FSharp.Data.Core.Tests/FSharp.Data.Core.Tests.fsproj --configuration Release
dotnet test tests/FSharp.Data.Core.Tests/FSharp.Data.Core.Tests.fsproj --configuration Release
dotnet test tests/FSharp.Data.Core.Tests/FSharp.Data.Core.Tests.fsproj /p:CollectCoverage=true /p:CoverletOutputFormat=cobertura
dotnet run --project build/build.fsproj -- -t Format

# Git commands
git checkout -b daily-test-improver-http-json-coverage
git add tests/FSharp.Data.Core.Tests/HttpContentTypes.fs tests/FSharp.Data.Core.Tests/JsonDocument.fs tests/FSharp.Data.Core.Tests/FSharp.Data.Core.Tests.fsproj
git commit -m "Daily Test Coverage Improver: Add comprehensive tests for HttpContentTypes and JsonDocument"
git push origin daily-test-improver-http-json-coverage
gh pr create --repo fsprojects/FSharp.Data --draft

Research and Analysis

• Analyzed current test coverage using coverlet and reportgenerator
• Identified 0% coverage areas through detailed coverage reports
• Reviewed existing test patterns in JsonConversions.fs and other test files
• Discovered private Helpers module in JsonConversions already well-tested
• Selected HttpContentTypes and JsonDocument as high-impact, achievable targets
• Used reflection approach for JsonDocument to work around compiler restrictions

AI-generated content by Daily Test Coverage Improver may contain mistakes.