csharp-test-coverage

name	csharp-test-coverage
description	Run C# tests with code coverage and report per-class/method line and branch coverage with uncovered line numbers. Accepts an optional test filter and optional class filter.
allowed-tools	["Bash(dotnet test:*)","Bash(reportgenerator:*)","Bash(node:*)","Bash(rm:*)","Read"]

Run C# tests with coverlet code coverage collection and produce a per-class coverage summary including uncovered line numbers for the classes you care about.

Arguments

• $ARGUMENTS — An optional string with two parts (both optional):

  • Test filter: a dotnet test --filter expression (e.g. FullyQualifiedName~TreatmentBMPControllerTests)
  • Class filter: prefixed with --classes followed by comma-separated partial class names to include in the report (e.g. --classes TreatmentBMPs,TreatmentBMPController)

  If no test filter is provided, all tests are run. If no class filter is provided, all classes with >0% coverage are shown.

Examples

/csharp-test-coverage FullyQualifiedName~TreatmentBMPControllerTests --classes TreatmentBMPs,TreatmentBMPController
/csharp-test-coverage --classes Projects,ProjectController
/csharp-test-coverage FullyQualifiedName~ExtensionMethodsTest
/csharp-test-coverage

Steps

1. Parse arguments from $ARGUMENTS:

   • Split on --classes to extract the test filter (before) and class name filters (after, comma-separated).
   • If no --classes flag, treat the entire argument as the test filter.

2. Run tests with coverlet to collect coverage in cobertura format:

   dotnet test Neptune.Tests/Neptune.Tests.csproj [--filter "<test-filter>"] -p:CollectCoverage=true -p:CoverletOutputFormat=cobertura -p:CoverletOutput=./coverage-results/ --no-restore
   

   • If a test filter was provided, include --filter "<test-filter>".
   • If tests fail, report the failure and stop.

3. Extract per-class coverage with uncovered lines using the helper script:

   node .claude/skills/csharp-test-coverage/parse-coverage.js Neptune.Tests/coverage-results/coverage.cobertura.xml [classFilter1,classFilter2,...]
   

   • If class name filters were provided, pass them as a comma-separated second argument.
   • The script outputs one JSON object per line with: class, file, lineCoverage, branchCoverage, uncoveredLines.
   • The uncoveredLines field contains line ranges (e.g. "18-20, 34-36") referring to the source file.

4. Present results as a markdown table with columns: Class, File, Line%, Branch%, Uncovered Lines.

   • For any class with uncovered lines, use the Read tool to read those specific lines from the source file so you can describe what code paths are not covered.
   • Summarize what specific test scenarios are missing to cover those lines.

5. Clean up temporary coverage files:

   rm -rf Neptune.Tests/coverage-results/
   

Notes

• The test project uses coverlet.msbuild (already a dependency in Neptune.Tests.csproj).
• reportgenerator is installed as a global dotnet tool.
• Coverage files are written to Neptune.Tests/coverage-results/ and cleaned up after reporting.
• The --no-restore flag speeds up the test run by skipping NuGet restore.
• The helper script parse-coverage.js lives alongside this SKILL.md and parses cobertura XML using Node.js.