How to test observable that emits multiple times on subscription in jasmine angular framework

I am having a service product.service.ts

class ProductService {

public product$: Observable<string> = from(['prod1','prod2','prod3','prod4']);

<other methods goes here...>

}

I want to test the below cases?

1. products$ observable should emit all the four values
2. third emitted data should be prod3

>Solution :

We can achieve this using jasmine.spy

it('should emit respective products'){
    const productsSpy = jasmine.createSpy();

    service.products$.subscribe(productsSpy);

    expect(productsSpy).toHaveBeenCalledTimes(4);
    expect(productsSpy.calls.argsFor(2)[0]).toBe('prod3');

}