title: How do I trigger the valuesChanged observable in a unit test after making changes to a FormGroup?
body: <p>I am writing unit testing code on a component that includes a reactive form (FormGroup) and a subscription to valueChanges and I haven't figured out how to ensure the valueChanges event gets emitted by the FormGroup.</p>
  
  <pre><code>// In the component under test:
  this.formGroup.get('field').valueChanges
       .subscribe((obj: any[]) =&gt; {
           debugger; // BREAKPOINT
           dataObject.fieldValues = [ ... ];
           ... details here should be unimportant ...
       });
  
  // In the unit test:
  it('should set dataObject from field component', fakeAsync(() =&gt; {
          [
      values: string[] = [ ... ];
  
      component.formGroup.get('field').setValue(values);
      component.formGroup.get('field').updateValueAndValidity({ emitEvent: true });
      fixture.detectChanges();
      tick();
  
      expect(component.dataObject.fieldValues.length).toEqual(values.length);
  
  }));
  
  </code></pre>
  
  <p>I can not get the unit test spec to hit the breakpoint in the component subscription code.</p>