StudiesObserver.test.js

import StudiesObserver from './StudiesObserver';

beforeEach(()=> {
  const studiesObserver = new StudiesObserver();
});

test('Changing the StudyBlock.status property should trigger update()', () => {
  const spy = jest.spyOn(studiesObserver, 'update');
  const isUpdating = studiesObserver.update();
  expect(spy).toHaveBeenCalled();
})

/* Jest error:

ReferenceError: studiesObserver is not defined 

const spy = jest.spyOn(studiesObserver, 'update');

*/