mo3ta-coverage

mo3ta-coverage checks coverage for changed lines in a pull request. It finds changed source files, maps them to likely test files, runs Jest in a selected execution mode, and validates changed-line coverage against a threshold.

Features

• Detects changed JS/TS files from all commits in the current branch, uncommitted changes, and staged files
• Maps changed source files to nearby test files automatically
• Supports three execution modes: fast, smart, and full
• Smart mode includes reverse dependency analysis with configurable depth
• Parses lcov.info and reports uncovered changed lines
• Enforces a minimum coverage threshold for changed lines
• Helpful error messages when invalid options are provided

Installation

npm install -g mo3ta-coverage

Usage

mo3ta-coverage --mode smart --base origin/main --limit 80

CLI Options

| Option | Description | Default | |--------|-------------|---------| | -v, --version | Output the current version | - | | --base <branch> | Base branch to compare against | origin/main | | --lcov <path> | Path to lcov.info | coverage/lcov.info | | --limit <percent> | Minimum changed-line coverage percentage | 80 | | --showCovered <bool> | Show covered changed lines in output | false | | --mode <mode> | Execution mode: fast, smart, or full (required) | smart | | --maxDepth <number> | Maximum reverse dependency depth for smart mode | 3 |

Modes

• fast: Direct execution of mapped test files only. No Jest dependency traversal. Fastest option.
• smart: Direct execution of changed source files plus mapped test files, with reverse dependency analysis. Includes tests for files that import your changes up to --maxDepth levels. Recommended for most projects.
• full: Runs mapped test files through jest --findRelatedTests. Let Jest expand to related tests. Use with caution in large projects.

If an invalid mode is provided, the tool will display available options with descriptions.

Recommended Mode

For most projects, especially large ones with shared helpers or deep import graphs, use:

mo3ta-coverage --mode smart --base origin/main --limit 80

Use full only when you intentionally want Jest to expand to related tests.

Configuration

You can persist defaults with the config subcommand:

mo3ta-coverage config --base origin/main --mode smart --maxDepth 3

This writes .mo3ta-coverage.json in the project root.

Changed Files Detection

The tool detects changed files by comparing against the specified base branch:

• All committed files in the current branch (from merge-base to HEAD)
• Uncommitted changes in the working tree
• Staged changes (files added with git add)

This means coverage is checked for all changes in your branch, not just your authored commits.

How It Works

1. Reads CLI options and saved config from index.js.
2. Finds changed source files from git in src/cli.js.
3. Maps source files to nearby test files in src/fileUtils.js.
4. Runs Jest in the selected mode from src/cli.js.
5. Parses lcov.info and reports uncovered changed lines.

Development

npm install
npm test

License

MIT