esm-learning

This repo demonstrates how to structure and evolve a modern TypeScript CLI and shared module architecture using npm workspaces, tsup, and npm pack — without needing to publish to a registry.

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📜 Evolution of the Project (Commit History)

✅ Commit 1: CLI with Shared Module Bundled

• Created two packages:
  • cli: a simple CLI that prints a greeting
  • shared: a module exporting greet(name)
• cli imported greet from @esm_learning/shared
• Used tsup to bundle shared into the CLI binary (noExternal)
• Packed CLI with npm pack
• Integration test installed the .tgz and ran the CLI via the bin script

✅ Good for simple tools, but tightly couples CLI and shared

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✅ Commit 2: CLI and Shared as Separately Publishable Modules

• Promoted shared to a standalone, versioned module
• Updated cli to treat @esm_learning/shared as an external dependency
• Introduced prepare-publish script to convert local "file:../shared" reference to real semver (^1.0.0) before packing
• Created end-to-end integration test that:
  • Packs both shared and cli into .tgz files
  • Simulates two consumers:
    • One imports and uses @esm_learning/shared
    • One installs and runs the CLI via bin

✅ This makes both packages portable, reusable, and testable without publishing to npm

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✅ Commit 3: Dynamic Plugin System in Shared + Custom Consumer Plugin

• Introduced a Plugin interface and PluginLoader class in shared
• Added runDefaultPlugin() which loads a built-in plugin via ts-node or dynamic import
• CLI updated to call runDefaultPlugin() after greeting the user
• End-to-end test updated to:
  • Create a library consumer that writes its own plugin class
  • Dynamically loads and runs that plugin using PluginLoader from @esm_learning/shared
  • Handles ESM/CJS compatibility and dynamic runtime paths

✅ Demonstrates extensibility: CLI + shared plugin system + consumer plugins — all tested locally

🧪 Testing Strategy

• Uses vitest to simulate real consumers
• Runs npm install on the .tgz files in fresh temp folders
• Verifies both library and CLI behavior
• Proves that local packaging workflows can fully replace registry publishing for testing and distribution

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🛠️ Stack

• TypeScript + tsup
• npm workspaces
• npm pack
• vitest
• CJS CLI with shebang
• ESM/CJS dual export for shared

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📝 License

ISC