Jest: Can't extract function that mocks a module

Question

I'm trying to find a simple and reusable way to mock responses from http requests. Right now I have:

// foo.test.ts 

jest.mock('axios');
import axios from 'axios';

describe('when updating user', () => {
  beforeEach(() => {
    (axios.post as jest.Mock).mockReturnValue({
      data: updatedUser,
    });
    result = foo();

But I'd rather simply pass my expected return value to a function I can reuse throughout my application:

// foo.test.ts

import { mockPost } from './mock'

describe('when updating user', () => {
  beforeEach(() => {
    mockPost(updatedUser);
    result = foo();
  })

So I tried to extract this mock into another module like so:

// mock.ts

jest.mock('axios');
import axios from 'axios';

export function mockPost(item: unknown) {
  (axios.post as jest.Mock).mockReturnValue({
    data: item,
  });
}

But alas, the module is no longer mocked. Is this impossible and if so, why?