coverage-report

name	coverage-report
description	Generate a .NET code coverage report scoped to files changed in the current branch. Runs tests with coverage collection and produces filtered HTML reports.
allowed-tools	Bash(dotnet test:*), Bash(dotnet reportgenerator:*), Bash(git diff:*), Bash(git merge-base:*), Bash(start:*), Read, Grep, Glob

Code Coverage Report

Generate a code coverage report scoped to source files changed in the current branch compared to a base branch.

Workflow

1. Determine base branch

Detect the base branch to diff against. Use the MR/PR target branch if known, otherwise default to main or master (whichever exists). Ask the user if ambiguous.

git merge-base --fork-point main HEAD || git merge-base --fork-point master HEAD

2. Detect changed source files

git diff <base-branch> --name-only -- '*.cs'

Filter out test files (paths containing Test, Tests, .Tests, .Test). If no source files changed, stop and inform the user.

3. Identify test project(s)

Determine which test project(s) to run. Strategies (in order):

1. User-specified: If the user names a test project, use it
2. Convention-based: Look for test projects whose name matches the changed project (e.g., MyProject -> MyProject.Tests)
3. Solution-wide: Run all tests in the solution if scope is unclear
4. Ask: If ambiguous, ask the user which test project(s) to run

4. Clean previous results

rm -rf TestResults/

5. Run tests with coverage

dotnet test <test-project-or-solution> \
  --collect:"XPlat Code Coverage" \
  --results-directory ./TestResults/

6. Build file filters

From the changed file list (step 2), extract basenames and build a filter string:

+*FileName1.cs;+*FileName2.cs;+*FileName3.cs

7. Generate report

dotnet reportgenerator \
  -reports:"TestResults/**/coverage.cobertura.xml" \
  -targetdir:"TestResults/CoverageReport" \
  -reporttypes:"Html;TextSummary" \
  -filefilters:"<filters>"

8. Display results

1. Print TestResults/CoverageReport/Summary.txt to the terminal
2. Open the HTML report (platform-aware):
   • Windows: start TestResults/CoverageReport/index.html
   • macOS: open TestResults/CoverageReport/index.html
   • Linux: xdg-open TestResults/CoverageReport/index.html

Tips

• For large solutions, scope to specific test projects to speed up collection
• The -filefilters flag accepts wildcards -- basename matching avoids path sensitivity