angular-testing_skill

Overview

This skill helps you write unit tests for Angular components, services, pipes, and directives using Vitest and Angular TestBed patterns. It provides templates, import guidance, and common patterns for mocking, async code, fake timers, and DOM queries to create consistent, reliable specs. Use it to produce test files colocated with source code and follow project conventions.

How this skill works

The skill generates test templates and explains what to import, how to configure TestBed, and how to provide zoneless change detection. It covers component, service, and directive testing patterns: creating fixtures, injecting services, mocking dependencies with vi, verifying HTTP calls with HttpTestingController, and asserting DOM state via debugElement and By. It also documents signal inputs, outputs, async handling, and fake timers.

When to use it

• When you need to create or update a .spec.ts file next to a source file
• When writing unit tests for Angular components, services, pipes, or directives
• When you want consistent Vitest patterns and TestBed configuration
• When you need examples for mocking services, HTTP requests, or external modules
• When testing inputs, outputs, signals, or DOM interactions

Best practices

• Place spec files alongside source files (component-name.spec.ts next to component-name.ts)
• Use provideZonelessChangeDetection() in providers to keep tests deterministic
• Follow AAA (Arrange, Act, Assert) and give tests descriptive names
• Mock external dependencies with vi.mock or provide value mocks via TestBed
• Verify HTTP expectations with HttpTestingController.verify() in afterEach

Example use cases

• Generate a component test that asserts rendering and button click behavior
• Create a service test that asserts an HTTP GET and flushes mock data
• Mock a dependency service to return synchronous or async values for a component
• Test a component signal input by setting the input before detectChanges
• Verify an EventEmitter output by subscribing to the emitter and asserting calls