How to test your schematic library?

Introduction

After creating your first schematics, you’ll want to test them to ensure they work as expected. There are three main ways to do this:

Watching mode

In your package.json, you’ll notice not just a build script but also a build:watch script. This command compiles your project automatically every time files in the src directory change.

To activate watching mode, execute:

npm run build:watch

Then, you can test your schematics using the CLI with the command: builder exec [collection-location] [schematic-name]. For example, to test it at the root of your project:

builder exec ./dist/collection.json prettier

Npm Link

If you want to test your schematics as if they were a package, you can use npm link. This approach allows you to simulate the installation and use of your package locally without publishing it. Execute the following:

npm run build && cd dist && npm link ./dist

Verdaccio

Verdaccio offers a more comprehensive testing setup with a few extra steps:

Install Verdaccio globally:

npm i -g verdaccio

Start the Verdaccio server:

verdaccio

Publish your package locally:

npm run build && cd dist && npm publish --registry http://localhost:4873

Verdaccio vs npm link

Here’s a comparison to help you decide between Verdaccio and npm link for testing your schematics:

Feature	Verdaccio	npm link
Primary Use	Acts as a private npm proxy registry for package management	Creates a symbolic link for local package development
Use Case	Ideal for managing private packages within teams or organizations	Useful for testing local changes in packages without needing to publish them
Advantages	- Private hosting of packages - Caching of npm packages - Version control - Integration with npm registry	- Quick feedback on changes - Simplifies the development process - Avoids premature package publication
Ideal For	Teams and organizations requiring shared access to private packages	Developers testing local package dependencies
Installation Process	Involves setting up a Verdaccio server	A straightforward command line operation
Security	Enhances package management security	Primarily for local development, minimal security impact
Network Dependency	Reduces reliance on the public npm registry by caching packages	No network dependency, as it links local packages directly

This documentation aims to make the process of testing your schematic library as straightforward as possible, providing you with multiple approaches to suit your development workflow.