Daily Test Coverage Improver - OpenAPI Routing Schema Tests

[dsyme]

Summary

This PR adds comprehensive tests for the OpenAPI routing schema generation code in Oxpecker.OpenApi/Routing.fs, significantly improving test coverage of previously untested code paths.

Changes Made

• Added 13 new test cases to tests/Oxpecker.OpenApi.Tests/Routing.Tests.fs
• Tests now properly exercise the getSchema function for all parameter type format specifiers:
  • %s (string) - %i (int) - %b (bool) - %c (char)
  • %d (int64) - %f (float) - %u (uint64) - %O (Guid/object)
• Tests verify the addOpenApiSimple type matching logic for all four type combinations:
  • unit request + unit response (InvokeUnit)
  • unit request + typed response (InvokeUnitReq)
  • typed request + unit response (InvokeUnitResp)
  • typed request + typed response (Invoke)
• Tests execute the .WithOpenApi() configuration callbacks to exercise schema parameter generation code

Test Coverage Results

Metric	Before	After	Change
Oxpecker.OpenApi/Routing.fs Line Coverage	31.71%	41.46%	+9.76%
Oxpecker.OpenApi/Routing.fs Branch Coverage	26.67%	26.67%	+0.00%
Overall Project Line Coverage	86.64%	86.91%	+0.27%
Overall Project Branch Coverage	62.94%	62.94%	+0.00%

Detailed Coverage Improvement

The new tests cover:

• Lines 13-25: The getSchema function that maps format characters to OpenAPI schemas
• Lines 32-45: The .WithOpenApi() configuration that adds parameters to operations
• Lines 59-60: The metadata configuration in addOpenApiSimple

These were previously completely untested (0% coverage).

Replicating the Test Coverage Measurements

To replicate these coverage measurements:

# Install dependencies and build
dotnet restore Oxpecker.sln
dotnet build Oxpecker.sln --no-restore

# Run tests with coverage
dotnet test Oxpecker.sln --no-restore --no-build \
  --collect:"XPlat Code Coverage" \
  --results-directory ./coverage-results

# Install ReportGenerator (if not already installed)
dotnet tool install -g dotnet-reportgenerator-globaltool

# Generate coverage report
reportgenerator \
  -reports:"./coverage-results/**/coverage.cobertura.xml" \
  -targetdir:"./coverage-report" \
  -reporttypes:"Html;Cobertura"

# View summary
python3 -c "
import xml.etree.ElementTree as ET
tree = ET.parse('./coverage-report/Cobertura.xml')
root = tree.getroot()
line_rate = float(root.attrib.get('line-rate', 0)) * 100
branch_rate = float(root.attrib.get('branch-rate', 0)) * 100
print(f'Line Coverage: {line_rate:.2f}%')
print(f'Branch Coverage: {branch_rate:.2f}%')
"

# Open HTML report
open ./coverage-report/index.html  # macOS
# or: xdg-open ./coverage-report/index.html  # Linux

Future Improvement Opportunities

Based on the coverage analysis, other areas with low coverage that could benefit from additional tests:

1. Oxpecker/Routing.fs - 56.76% line coverage (various routing helpers)
2. Oxpecker.ViewEngine/Builder.fs - 51.61% line coverage (HTML builder functionality)
3. Oxpecker/Core.fs, ModelBinder.fs, HttpContextExtensions.fs - 0% coverage (utility functions)
4. Oxpecker.ViewEngine/IdeTweaks.fs - 0% coverage (IDE-specific helpers)

Testing Strategy

The tests use a mock IEndpointConventionBuilder to execute the configuration callbacks without requiring a full ASP.NET Core application context. This approach:

• Allows isolated testing of the schema generation logic
• Exercises the actual code paths without complex infrastructure
• Validates that all type format specifiers produce appropriate OpenAPI schemas

Commands Executed

# Coverage analysis
dotnet restore Oxpecker.sln
dotnet build Oxpecker.sln --no-restore
dotnet test Oxpecker.sln --no-restore --no-build --collect:"XPlat Code Coverage" --results-directory ./coverage-results
dotnet tool install -g dotnet-reportgenerator-globaltool
reportgenerator -reports:"./coverage-results/**/coverage.cobertura.xml" -targetdir:"./coverage-report" -reporttypes:"Html;Cobertura"

# Test development  
git checkout -b test-coverage/openapi-routing-schema-tests
dotnet build tests/Oxpecker.OpenApi.Tests/Oxpecker.OpenApi.Tests.fsproj
dotnet test tests/Oxpecker.OpenApi.Tests/Oxpecker.OpenApi.Tests.fsproj --no-build

# Re-validate coverage improvement
dotnet test Oxpecker.sln --no-restore --no-build --collect:"XPlat Code Coverage" --results-directory ./coverage-results-after
reportgenerator -reports:"./coverage-results-after/**/coverage.cobertura.xml" -targetdir:"./coverage-report-after" -reporttypes:"Html;Cobertura"

Web Searches Performed

None

Web Pages Fetched

None

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