Umbraco Unit Testing

This handles unit testing for Umbraco backoffice extensions built with Lit and Web Components, using the @open-wc/testing framework. You get two approaches: full integration with Umbraco's context system for testing real component behavior, or a mock-based setup that's simpler and faster when you just need to test state logic and observables in isolation. The documentation is thorough about the import path gotchas (dist-cms versus dist/packages trips people up) and includes working examples from the tree-example extension. If you're building custom property editors or workspace components, this gives you the test infrastructure to catch rendering bugs and state management issues before they hit the backoffice.

skills.sh installs: 374
GitHub stars: 27
last updated: Aug 21, 2026

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Install

$ npx -y skills add umbraco/umbraco-cms-backoffice-skills --skill umbraco-unit-testing --agent claude-code

Installs into .claude/skills of the current project.

Files

Umbraco Unit Testing

What is it?

Unit testing for Umbraco backoffice extensions using @open-wc/testing - a testing framework designed for Web Components and Lit elements. This is the fastest and most isolated testing approach.

When to Use

Testing context logic and state management
Testing Lit element rendering and shadow DOM
Testing observable subscriptions and state changes
Testing controllers and utility functions
Fast feedback during development

Related Skills

umbraco-testing - Master skill for testing overview
umbraco-msw-testing - Add API mocking to unit tests

Documentation

@open-wc/testing: https://open-wc.org/docs/testing/testing-package/
Web Test Runner: https://modern-web.dev/docs/test-runner/overview/

Setup

Dependencies

Add to package.json:

{
  "devDependencies": {
    "@open-wc/testing": "^4.0.0",
    "@web/dev-server-esbuild": "^1.0.0",
    "@web/dev-server-import-maps": "^0.2.0",
    "@web/test-runner": "^0.18.0",
    "@web/test-runner-playwright": "^0.11.0"
  },
  "scripts": {
    "test": "web-test-runner",

SKILL.md on GitHub