Oclif Patterns

oclif Enterprise CLI Patterns

Provides comprehensive patterns for building production-grade CLIs with oclif framework.

Core Capabilities

1. Command Structure

• Single and multi-command CLIs
• Flag definitions (string, boolean, integer, custom)
• Argument parsing with validation
• Command inheritance and base classes
• Async command execution

2. Plugin System

• Installable plugins
• Plugin discovery and loading
• Hook system for extensibility
• Plugin commands and lifecycle

3. Auto-Documentation

• Auto-generated help text
• README generation
• Command reference docs
• Flag and argument documentation

4. Testing Patterns

• Command unit tests
• Integration testing
• Mock stdin/stdout
• Fixture management
• Test helpers

Implementation Guide

Command Creation

Use templates:

• templates/command-basic.ts - Simple command with flags
• templates/command-advanced.ts - Complex command with validation
• templates/command-async.ts - Async operations
• templates/base-command.ts - Custom base class

Key patterns:

1. Import Command from '@oclif/core'
2. Define flags using Flags object
3. Define args using Args object
4. Implement async run() method
5. Use this.log() for output
6. Use this.error() for errors

Flag Patterns

Common flags:

• String: Flags.string({ description, required, default })
• Boolean: Flags.boolean({ description, allowNo })
• Integer: Flags.integer({ description, min, max })
• Custom: Flags.custom<T>({ parse: async (input) => T })
• Multiple: Flags.string({ multiple: true })

Best practices:

• Always provide clear descriptions
• Use char for common short flags
• Set required vs optional explicitly
• Provide sensible defaults
• Validate in parse function for custom flags

Argument Patterns

Definition:

static args = {
  name: Args.string({ description: 'Name', required: true }),
  file: Args.file({ description: 'File path', exists: true })
}

Access in run():

const { args } = await this.parse(MyCommand)

Plugin Development

Use templates:

• templates/plugin-package.json - Plugin package.json
• templates/plugin-command.ts - Plugin command structure
• templates/plugin-hooks.ts - Hook implementations

Plugin structure:

my-plugin/
├── package.json (oclif configuration)
├── src/
│   ├── commands/ (plugin commands)
│   └── hooks/ (lifecycle hooks)
├── test/ (plugin tests)
└── README.md

Testing Setup

Use templates:

• templates/test-command.ts - Command test template
• templates/test-helpers.ts - Test utilities
• templates/test-setup.ts - Test configuration

Testing approach:

1. Use @oclif/test for test helpers
2. Mock stdin/stdout with fancy-test
3. Test flag parsing separately
4. Test command execution
5. Test error handling
6. Use fixtures for file operations

Auto-Documentation

Generated automatically:

• Command help via --help flag
• README.md with command reference
• Usage examples
• Flag and argument tables

Use scripts:

• scripts/generate-docs.sh - Generate all documentation
• scripts/update-readme.sh - Update README with commands

Quick Start Examples

Create Basic Command

# Use template
./scripts/create-command.sh my-command basic

# Results in: src/commands/my-command.ts

Create Plugin

# Use template
./scripts/create-plugin.sh my-plugin

# Results in: plugin directory structure

Run Tests

# Use test helpers
npm test
# or with coverage
npm run test:coverage

Validation Scripts

Available validators:

• scripts/validate-command.sh - Check command structure
• scripts/validate-plugin.sh - Verify plugin structure
• scripts/validate-tests.sh - Ensure test coverage

Templates Reference

TypeScript Commands

1. command-basic.ts - Simple command pattern
2. command-advanced.ts - Full-featured command
3. command-async.ts - Async/await patterns
4. base-command.ts - Custom base class
5. command-with-config.ts - Configuration management

Plugin System

6. plugin-package.json - Plugin package.json
7. plugin-command.ts - Plugin command
8. plugin-hooks.ts - Hook implementations
9. plugin-manifest.json - Plugin manifest

Testing

10. test-command.ts - Command unit test
11. test-helpers.ts - Test utilities
12. test-setup.ts - Test configuration
13. test-integration.ts - Integration test

Configuration

14. tsconfig.json - TypeScript config
15. package.json - oclif package.json
16. .eslintrc.json - ESLint config

Examples Directory

See examples/ for complete working examples:

• examples/basic-cli/ - Simple CLI with commands
• examples/plugin-cli/ - CLI with plugin support
• examples/enterprise-cli/ - Full enterprise setup

Common Patterns

Error Handling

if (!valid) {
  this.error('Invalid input', { exit: 1 })
}

Spinner/Progress

const spinner = ux.action.start('Processing')
// ... work
ux.action.stop()

Prompts

const answer = await ux.prompt('Continue?')

Table Output

ux.table(data, { columns: [...] })

Requirements

• Node.js 18+
• TypeScript 5+
• @oclif/core ^3.0.0
• @oclif/test for testing
• Knowledge of TypeScript decorators (optional but helpful)

Best Practices

1. Command Design: Keep commands focused, single responsibility
2. Flags: Use descriptive names, provide help text
3. Testing: Test command parsing and execution separately
4. Documentation: Let oclif generate docs, keep them updated
5. Plugins: Design for extensibility from the start
6. Error Messages: Provide actionable error messages
7. TypeScript: Use strict mode, define proper types
8. Async: Use async/await, handle promises properly

Advanced Features

Custom Flag Types

Create reusable custom flag parsers for complex validation.

Hook System

Implement hooks for: init, prerun, postrun, command_not_found.

Topic Commands

Organize commands into topics (e.g., mycli topic:command).

Auto-Update

Use @oclif/plugin-update for automatic CLI updates.

Analytics

Integrate analytics to track command usage.

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