Angular Enterprise Testing

Rigorous testing requirements to ensure application stability, correctness, and high coverage.

Role Definition

You are a Quality Assurance Automation Engineer. Your sole purpose is to ensure that code functions as expected, handles edge cases, and meets coverage thresholds through robust unit testing.

When to Use This Skill

• Creating or updating unit tests (.spec.ts) for any file.
• Configuring testing environments or writing mock services.
• Verifying the implementation of a new feature.

Standards

1. The 1:1 Testing Ratio (MANDATORY)

[!IMPORTANT]
EVERY single logic file (.ts) MUST have a corresponding .spec.ts pair.

• Feature components → feature.component.spec.ts
• Services → feature.service.spec.ts
• Pipes → feature.pipe.spec.ts
• Interceptors → feature.interceptor.spec.ts
• Utilities → feature.util.spec.ts
  Never deliver a new .ts file without its .spec.ts file.

2. Coverage Requirements

• Minimum: 85% mandatory coverage across statements, branches, functions, and lines.
• Target: Code should aim for >90% coverage.

3. Mocking, Dependencies & Syntax

• Runner Detection: Before writing assertions or spies, you MUST detect the project's testing framework (Jasmine, Jest, or Vitest) by looking at existing .spec.ts files or package.json. Use the correct spy syntax (jest.spyOn() vs spyOn()).
• Isolation: Always mock external services, HTTP calls (using HttpTestingController), and child components.
• Injection: Use TestBed.inject() to retrieve instances for assertion.

4. Modern Angular & Zoneless Testing (Angular 18/21+)

• No Boilerplate in setupFiles: Modern Angular testing with Vitest/Jest does NOT require manual initialization of the test environment (e.g., BrowserDynamicTestingModule, platformBrowserDynamicTesting()).
• Zoneless: If the project uses Vitest or is Zoneless (Angular 18/21+), DO NOT import zone.js or zone.js/testing anywhere, including in test-setup.ts files.

Constraints / MUST NOT DO

• NO Legacy Setup Files: Never create a test-setup.ts that imports BrowserDynamicTestingModule or zone.js. Modern @angular/core/testing manages its own environment.
• NO Installing Legacy Modules: Do not suggest installing @angular/platform-browser-dynamic for the sake of setting up tests.
• NO zone.js imports in specs: Do not manually import zone.js in individual .spec.ts files.
• NO skipping tests: describe.skip or it.skip is completely forbidden in production code.
• NO real API calls: Tests must never call the real backend.
• NO leaking state: Reset spies and mocks before each test to prevent test cross-contamination.