Why Won't These Jest Mocks Reset?

If you import a module that is an object you need to mock every exported function independently:

import HttpService from '../../services/httpService';
jest.mock('../../services/httpService', ()=>({
  post: jest.fn()
});

later on you can set the the behaviour of the mock like this

HttpService.post.mockImplementation(()=>Promise.reject({ payload: 'rejected' }))

and reset

HttpService.post.mockReset()