Peer Dependency Helper CLI Tool

Table of Contents

• Introduction
• Features
• Installation
• Usage
  • Commands
  • Global Options
  • Audit Command
  • Fix Command
• Configuration
• Core Concepts
  • How it Works
  • Version Resolution Strategies
• Advanced Features
  • Caching
  • Monorepo Support
• Testing
• Contributing
• Troubleshooting
• License

Introduction

peer-dep-helper is a powerful Command Line Interface (CLI) tool designed to streamline the management of peer dependencies in Node.js projects. It helps developers detect, audit, and automatically fix common issues related to peer dependencies, ensuring project stability and preventing unexpected runtime errors.

Features

• Comprehensive Auditing: Scans your project's node_modules and package.json to identify missing or mismatched peer dependencies.
• Automated Fixing: Automatically installs correct versions of missing or mismatched peer dependencies.
• Flexible Configuration: Supports configuration via CLI flags and a .peer-dep-helperrc file.
• Multiple Strategies: Offers different version resolution strategies (strict, compatible, latest) to suit various project needs.
• JSON Output: Provides an option to output reports in JSON format for integration with other tools.
• Monorepo Awareness: Designed with future support for monorepo structures.
• Caching: Includes a caching mechanism for faster subsequent scans.

Installation

To install peer-dep-helper globally, use your preferred package manager:

1npm install -g peer-dep-helper
2# OR
3yarn global add peer-dep-helper
4# OR
5pnpm add -g peer-dep-helper

Usage

The peer-dep-helper tool provides two main commands: audit and fix.

Commands

peer-dep-helper audit

Scans your project for peer dependency issues and prints a detailed report. This is the default command if no other command is specified.

peer-dep-helper fix

Detects peer dependency issues and attempts to automatically install or suggest the correct versions.

Global Options

These options can be used with any command.

• --json: Output the report as JSON.
  • Example: peer-dep-helper audit --json
• --silent: Suppress all terminal output except errors.
  • Example: peer-dep-helper audit --silent
• --cwd <path>: Specify a custom working directory for the scan. Defaults to the current working directory.
  • Example: peer-dep-helper audit --cwd ./my-project
• --strategy <strategy>: Define the version resolution strategy.
  • Accepted values: strict, compatible (default), latest.
  • Example: peer-dep-helper audit --strategy strict
• --dry-run: (Applicable to fix command) Show what would be installed/changed without making any actual modifications.
  • Example: peer-dep-helper fix --dry-run
• --fail-on-issues: Exit with a non-zero code if issues are found. Useful for CI/CD pipelines.
  • Example: peer-dep-helper audit --fail-on-issues

Audit Command Options

• --fix: Automatically apply fixes after auditing. This is a convenience flag for the audit command that triggers the fix logic.
  • Example: peer-dep-helper audit --fix

Fix Command Options

• --write: Write fixed dependencies to the root package.json file.
  • Example: peer-dep-helper fix --write
• --only <packages...>: Fix only specified packages. Provide a comma-separated list of package names.
  • Example: peer-dep-helper fix --only react,react-dom

Configuration

peer-dep-helper can be configured using a .peer-dep-helperrc file (JSON or YAML format) in your project's root directory. CLI flags will always override settings from the configuration file.

The following configuration options are available:

• cwd: Specify a custom working directory for the scan. Defaults to the current working directory.
• ignore: Specify an array of packages to ignore during the scan.

Example .peer-dep-helperrc.json:

1{
2  "strategy": "strict",
3  "silent": false,
4  "ignore": [
5    "some-package-to-ignore",
6    "another-package-to-ignore"
7  ]
8}

Note: The ignore option is mentioned in bin/index.js but not explicitly defined in PLAN.md or REFINEMENT_PLAN.md as a configurable option. Its behavior should be clarified.

Core Concepts

How it Works

The tool operates by:

1. Parsing Configuration: Loads CLI arguments and merges them with settings from .peer-dep-helperrc.
2. Scanning: Reads the root package.json and recursively scans the node_modules directory to identify all installed packages and their declared peerDependencies.
3. Issue Detection: For each peerDependency, it checks if the required peer is:
   • Missing from the root node_modules.
   • Installed but with a version that does not satisfy the declared range (using semantic versioning).
4. Issue Classification: Issues are classified as missing or version_mismatch.
5. Version Resolution: Determines the correct version range based on the chosen --strategy.
6. Reporting: Formats and outputs the detected issues to the console or as JSON.
7. Fixing (Optional): If the fix command or --fix flag is used, it constructs and executes appropriate package manager commands (npm install, yarn add, pnpm add) to resolve the issues. It can optionally update the root package.json.

Version Resolution Strategies

The --strategy option dictates how peer-dep-helper resolves required peer dependency versions.

• compatible (Default): Aims to find a version that satisfies all declared peer dependency ranges. If multiple ranges exist for the same peer, it attempts to find the broadest compatible version.
• strict: Requires that the installed peer dependency exactly matches the version specified by the peer dependency range. This strategy is less forgiving and will flag more issues.
• latest: Attempts to resolve the peer dependency to its latest available version that still satisfies the declared range. (Further refinement needed: Currently, this might rely on locally installed versions or require network calls, which are generally out of scope for this tool's current design. Its exact behavior should be clarified and documented.)

Advanced Features

Caching

peer-dep-helper utilizes a caching mechanism to speed up repeated scans. Analysis results are stored in a .peer-dep-helper-cache.json file.

• Invalidation: The cache invalidation logic is designed to be robust, using content hashing of package.json and lock files. See lib/scan.js documentation for details.
• Clearing Cache: To clear the cache, manually delete .peer-dep-helper-cache.json in your project root. (A CLI option for clearing cache may be added in the future.)

Monorepo Support

The tool is being developed with monorepo environments in mind. It aims to:

• Detect Workspaces: Identify workspaces configured by package managers like Yarn, pnpm, or Lerna.
• Scan Nested package.json files: Ensure all relevant package.json files within a monorepo are scanned for peer dependencies.
• Pnpm Workspaces: Specifically, it will consider parsing pnpm-workspace.yaml for accurate workspace path determination.
• See lib/utils.js documentation for workspace detection details.

Testing

The project uses jest for comprehensive testing. See Testing Documentation.

• Unit Tests: Cover individual modules (scan.js, fix.js, utils.js, config.js, output.js).
• Integration Tests: Utilize a fixtures/ directory containing various test projects to simulate real-world scenarios (e.g., projects with missing peers, version mismatches, no issues, monorepo examples). See Fixtures Documentation.
• Mocking: fs/promises and execa are mocked to prevent actual file system changes or command executions during tests.

Contributing

See CONTRIBUTING.md for guidelines on setting up the development environment, running tests, and submitting pull requests.

Troubleshooting

• "Error: Command not found": Ensure peer-dep-helper is installed globally and your system's PATH includes the global npm/yarn/pnpm bin directory.
• Unexpected Issues: If you encounter unexpected issues, try running the command with --silent removed to see debug logs.
• Cache Issues: If results seem stale, manually delete .peer-dep-helper-cache.json to clear the cache.

License

This project is licensed under the MIT License. See the package/license file for details.

Further Documentation

• CLI Entrypoint Documentation
• lib/scan.js
• lib/fix.js
• lib/output.js
• lib/utils.js
• lib/config.js
• package/lib/command.js
• package/lib/error.js
• package/lib/kill.js
• package/lib/promise.js
• package/lib/stdio.js
• package/lib/stream.js

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