title: how to get arguments on an event emitter in jasmine test
body: <p>I have a unit test as below</p>
  
  <pre><code>it('billing information is correct', () =&gt; {
      fixture.detectChanges();
      spyOn(component.myEventEmitter, 'emit').and.callThrough();
      component.form.controls['size'].setValue(12);
      fixture.detectChanges();
      **let args= component.myEventEmitter.emit.mostRecentCall **
      expect(args.billingSize).toEqual('30')
  });
  </code></pre>
  
  <p>When size changes, myEventEmitter is being emitted with a large json object which includes billingSize. And I want the test to check if this value is as expected. But looks like I can't do 'mostRecentCall/ calls' on the event emitter. any suggestions??</p>
  
  <p>Note: I don't want to do </p>
  
  <pre><code> expect(component.myEventEmitter.emit).toHaveBeenCalledWith(*dataExpected*);
  </code></pre>
  
  <p>because the dataExpected is a large json object. I just care about one field. Any help would be much appreciated.</p>