How can I mock data for this.getResults$.subscribe in angular for unit test cases?

Question

displayMesssage(){
this.getResults$.subscribe(data =>{
if(data !== undefined && data !== null){
 this.message = data.message;
}else{
 this.message="Empty";
});
}

How can I mock data for the above use case in jasmine?

Answer 1

Something like this, it may work. If this doesn't work, I need to see the full spec and full component.

import { of } from 'rxjs';
....
it('should set message to data.message when not null or undefined', () => {
  component.getResults$ = of({ message: 'hello world' });
  component.displayMessage();
  expect(component.message).toBe('hello world');
});

it('should set message to "Empty" if getResults$ is falsy', () => {
  component.getResults$ = of(null);
  component.displayMessage();
  expect(component.message).toBe('Empty');
});