Coverage Comparison Action

A GitHub Action that compares code coverage between branches by analyzing coverage reports stored in Google Cloud Storage. This action supports Java, JavaScript, and Python coverage formats.

Features

• Compares code coverage between base and head branches in pull requests
• Supports multiple programming languages (Java, JavaScript, Python)
• Creates or updates PR comments with detailed coverage information
• Shows coverage trends with visual indicators (📈 📉)
• Highlights files with significant coverage changes
• Optional display of uncovered line ranges
• Fails the check if coverage falls below minimum threshold
• Tracks new files and coverage changes in PR-modified files
• Intelligently handles path prefixes (e.g., python_coverage/) to match files between PR changes and coverage reports
• New: Supports .coveragerc configuration file

.coveragerc Support

The action now supports reading a .coveragerc file in your repository. This allows you to:

• Specify files to be omitted from coverage reports
• Configure coverage measurement settings

Omitting Files

In your .coveragerc file, you can use the omit section under [run] to exclude specific files or patterns from coverage reports:

[run]
omit =
    **/test_files/**
    src/ignored_file.py
    tests/*

Files matching these patterns will:

• Be excluded from the list of uncovered files
• Not trigger coverage warnings or failures

This feature is particularly useful for:

• Excluding test files
• Ignoring generated code
• Skipping files that don't require full coverage

Flexible Matching:

• Patterns can match full paths or individual file/directory names
• Works across different project structures
• Supports wildcard and glob-style patterns

Usage

This action is typically used in conjunction with a coverage upload action. Here's a complete example:

name: Coverage Check

on:
  pull_request:
    branches: [master]

jobs:
  # First job: Run tests and upload coverage
  test-upload-coverage:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        python-version: ['3.10', '3.11', '3.12']

    steps:
      - uses: actions/checkout@v3

      # Run your tests and generate coverage
      - name: Generate coverage report
        run: |
          pip install coverage
          coverage run -m unittest discover
          coverage report -m
          coverage xml

      # Upload the coverage report
      - name: Upload coverage
        uses: baobabsoluciones/upload-coverage@v0.0.15
        with:
          python-version: ${{ matrix.python-version }}
          gcp-project-id: ${{ secrets.GCP_PROJECT_ID }}
          gcp-credentials: ${{ secrets.GCP_CREDENTIALS }}
          gcp-coverage-bucket: ${{ secrets.GCP_COVERAGE_BUCKET }}

  # Second job: Compare coverage
  coverage-check:
    needs: test-upload-coverage
    runs-on: ubuntu-latest
    steps:
      - uses: baobab-soluciones/coverage-action@v1
        with:
          gcp_credentials: ${{ secrets.GCP_CREDENTIALS }}
          github_token: ${{ secrets.GITHUB_TOKEN }}
          gcp_bucket: ${{ secrets.GCP_COVERAGE_BUCKET }}
          min_coverage: '80'
          show_missing_lines: 'true'

Inputs

Input	Description	Required	Default
gcp_credentials	Google Cloud Service Account credentials JSON	Yes	-
github_token	GitHub token for PR comments	Yes	-
gcp_bucket	GCP bucket name where coverage reports are stored	Yes	-
min_coverage	Minimum required coverage percentage	No	80
show_missing_lines	Show missing lines in coverage report	No	false

Coverage Report Format

The action expects coverage reports to be stored in Google Cloud Storage with the following structure:

bucket/
└── repository-name/
    └── branch-name/
        └── timestamp/
            └── coverage.xml

Path Handling

The action automatically normalizes paths between PR changes and coverage reports. For example, if your PR shows changes in:

python_coverage/module/example.py

But your coverage report has paths like:

module/example.py

The action will automatically match these files by removing common prefixes (like python_coverage/). This ensures accurate coverage tracking regardless of path differences between your PR and coverage reports.

Output Example

The action will create or update a comment in your PR that looks like this:

@@ Coverage Diff @@
## main    #feature    +/-  ##
===========================================
  Coverage     85.00%    87.50%    +2.50% 📈
===========================================
  Files            10        11        +1
  Lines           200       220       +20
  Branches         50        55        +5
===========================================
  Hits            170       192       +22 📈
  Misses           25        23        -2 📈
  Partials          5         5         0 📈

@@ File Coverage Diff @@
  src/index.js     80.00%    85.00%    +5.00% 📈
- src/utils.js     90.00%    85.00%    -5.00% 📉
+ src/new-file.js   0.00%    75.00%   +75.00% 📈

Requirements

• Coverage reports must be in XML format (Cobertura format)
• Coverage reports must be stored in Google Cloud Storage
• The action must be run on pull request events
• GCP credentials with read access to the storage bucket
• GitHub token with permissions to comment on PRs

License

This project is licensed under the Apache 2.0 License - see the LICENSE file for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.