🛡 Diff Cover Action
Report test coverage and code quality only on changed lines in your GitHub pull requests. Zero vendor lock-in.
Features
Diff Coverage
Find lines in your PR that aren't covered by tests. Supports Cobertura XML, lcov, JaCoCo, and Clover reports.
Diff Quality
Find lint and style violations only in changed code. Supports 13+ tools across Python, JavaScript, C++, and shell.
PR Comments
Auto-posted, idempotent comments that update on re-run instead of spamming your pull request.
Inline Annotations
Uncovered lines and violations appear directly in the PR diff view as warnings, errors, or notices.
Step Summaries
Coverage and quality tables appear in the GitHub Actions run UI — visible without opening the PR.
Zero Vendor Lock-in
Everything runs locally in the GitHub Actions runner. No external services, no accounts, no data leaving your CI.
Quick Start
# .github/workflows/coverage.yml
name: Coverage
on: [pull_request]
permissions:
contents: read
pull-requests: write
jobs:
test:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v4
- name: Run tests with coverage
run: |
pip install pytest pytest-cov
pytest --cov --cov-report=xml
- name: Diff Coverage
uses: Affanmir/diff-cover-action@v1
with:
coverage-files: coverage.xml
fail-under: '80'Supported Tools
Works with any language that produces standard coverage reports.
| Category | Tools |
|---|---|
| Coverage formats | Cobertura XML, lcov, JaCoCo XML, Clover XML |
| Python linters | ruff, flake8, pylint, pycodestyle, pyflakes, mypy, pydocstyle |
| JavaScript linters | eslint, jshint |
| Other | checkstyle, checkstylexml, clang, cppcheck, shellcheck |