Question 1

How do you unit test an Angular component with TestBed?

Accepted Answer

Configure TestBed with the component and stubs, create fixture, detectChanges, assert DOM/state. Prefer shallow tests with mocked services. Use harnesses for CDK. Prefer testing library queries for a11y-friendly asserts.

Question 2

How do you test a service that uses HttpClient?

Accepted Answer

Use HttpClientTestingModule / provideHttpClientTesting and HttpTestingController to flush responses. Assert method, URL, and body. Verify no outstanding requests. Don't hit real network in unit tests.

Question 3

What is the difference between isolated unit tests and integration component tests?

Accepted Answer

Unit tests mock collaborators heavily; integration tests wire more of Angular and child components. Balance speed vs confidence. Use e2e (Playwright/Cypress) for critical user journeys.

Question 4

How do you test route guards?

Accepted Answer

Call the guard function with mock routers/auth state and assert boolean/UrlTree results. With functional guards, inject deps via TestBed.runInInjectionContext. Cover authorized and unauthorized paths.

Question 5

Lead approach: what testing strategy do you set for an Angular team?

Accepted Answer

Pyramid: many fast unit tests, fewer component integration tests, selective e2e; CI required; shared testing utilities. Ban flaky e2e as merge blockers without quarantine. Contract-test APIs. Budget time for a11y checks.

Testing Angular Interview Questions

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