Unit test a subscription in ngOnInit not working

Question

I have subsriber to an observable on ngOnInit and now I am trying to write test for this which doesn't seems working.

Here is my class which I am trying to test

ngOnInit() {
  this.myService.updates$.pipe(takeUntil(unsusbribe$))
   .subscribe(update => {
     this.feeds = update;
  })
}

Here is my unit test for this

it('should set feeds when an update is sent', fakeAsync(() => {
const update = 'fakeUpdate';
component.ngOnInit();
  const serviceSpy = spyOn(myService, 'updates$').and.returnValue(timer(500).pipe(mapTo(update)))
tick(500);
expect(serviceSpy).toHaveBeenCalled(); 
}))

This test fails with error Expected spy updates$ to have been called.

Can anyone please help me figuring out the issue here.

Where is ngOnInit being called in your test? If it isn't called, why would your spy be called? — JB Nizet, Mar 07 '19 at 11:19
@JBNizet I just updated question... its been called on ngOnInit(). So I have called component.ngOnInit() — undefined, Mar 07 '19 at 11:38

score 0 · Answer 1 · answered Mar 07 '19 at 11:30

0

Correct way to use spy service. Please try this one.

  it('should set feeds when an update is sent', fakeAsync(() => {
    const update = 'fakeUpdate';
    const serviceSpy = spyOn(myService, 'updates$');
    serviceSpy.and.returnValue(timer(500).pipe(mapTo(update)))
    tick(500);
    expect(serviceSpy).toHaveBeenCalled(); 
  }))

answered Mar 07 '19 at 11:30

Mohit Saxena

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Thanks for your help but this still seems not working. – undefined Mar 07 '19 at 11:42

Unit test a subscription in ngOnInit not working

1 Answers1