Mock setTargetNoteHash instead of handleHashChanged

spec/frontend/notes/components/note_app_spec.js

@@ -10,6 +10,7 @@ import '~/behaviors/markdown/render_gfm';
 import { setTestTimeout } from 'helpers/timeout';
 // TODO: use generated fixture (https://gitlab.com/gitlab-org/gitlab-foss/issues/62491)
 import * as mockData from '../../notes/mock_data';
+import * as urlUtility from '~/lib/utils/url_utility';
 
 setTestTimeout(1000);
 
@@ -324,11 +325,14 @@ describe('note_app', () => {
     });
 
     it('should listen hashchange event', () => {
-      wrapper.vm.$refs.notesApp.handleHashChanged = jest.fn();
-      // jest.spyOn(wrapper.vm.$refs.notesApp, 'handleHashChanged');
-      window.dispatchEvent(new Event('hashchange'), '#foo');
+      const notesApp = wrapper.find(NotesApp);
+      const hash = 'some dummy hash';
+      jest.spyOn(urlUtility, 'getLocationHash').mockReturnValueOnce(hash);
+      const setTargetNoteHash = jest.spyOn(notesApp.vm, 'setTargetNoteHash');
 
-      expect(wrapper.vm.$refs.notesApp.handleHashChanged).toHaveBeenCalled();
+      window.dispatchEvent(new Event('hashchange'), hash);
+
+      expect(setTargetNoteHash).toHaveBeenCalled();
     });
   });
 });