Angular Web Framework Testing & Debugging 2

Question 1

Which Angular testing utility method is used to trigger change detection manually in a component test?

Accepted Answer

fixture.detectChanges()

Answer

fixture.detectChanges() triggers Angular's change detection cycle so the view reflects the component's current state.

Question 2

What is the purpose of the `NO_ERRORS_SCHEMA` in Angular unit tests?

Accepted Answer

It suppresses errors from unknown elements and attributes in templates

Answer

NO_ERRORS_SCHEMA tells Angular to ignore unknown elements and attributes, simplifying shallow component testing without declaring child components.

Question 3

In Angular, what does `fakeAsync` combined with `tick()` allow you to test?

Accepted Answer

Asynchronous code by simulating the passage of time

Answer

fakeAsync wraps the test in a fake asynchronous zone, and tick() advances the virtual clock to resolve timers and Promises.

Question 4

Which method on a Jasmine spy allows you to define what value it returns when called?

Accepted Answer

spy.and.returnValue()

Answer

spy.and.returnValue() configures a Jasmine spy to return a specific value every time the spied function is invoked.

Question 5

When testing an Angular service that uses HttpClient, which module should be imported in TestBed?

Accepted Answer

HttpClientTestingModule

Answer

HttpClientTestingModule replaces HttpClient with a mock backend (HttpTestingController) that lets you inspect and flush HTTP requests in tests.

Angular Web Framework Practice Test