How do I test Angular observables effectively?

How do I test Angular observables effectively?

To test Angular observables, you can use the TestBed utility along with RxJS testing utilities like 'marble testing'. Would you like a code example?

Yes, please provide a code example for testing an observable.

Here's a simple example:

import { TestBed } from '@angular/core/testing';
import { of } from 'rxjs';
import { MyService } from './my.service';

describe('MyService', () => {
  let service: MyService;

  beforeEach(() => {
    TestBed.configureTestingModule({
      providers: [MyService]
    });
    service = TestBed.inject(MyService);
  });

  it('should return expected data', (done) => {
    const expectedData = 'test data';
    spyOn(service, 'getData').and.returnValue(of(expectedData));

    service.getData().subscribe(data => {
      expect(data).toEqual(expectedData);
      done();
    });
  });
});

This tests that the observable returns the expected data.

What are marble tests and how do I use them?

Marble tests are a way to test observables in a visual and declarative manner. You can use the 'rxjs/testing' library to create marble diagrams that represent the emissions over time. Would you like a marble testing example?