didn't mockReset created by shallwefootball - https://repl.it/Feas/8

config.json

{
  "testRegex": ".*-test.js",
  "testEnvironment": "node"
}

fetch-test.js

const fetch = require('./fetch');
describe('fetch', () => {
  it('called with GET', () => {
    fetch.req = jest.fn();
    fetch.reqGet();
    expect(fetch.req).toBeCalledWith('GET');
  });
  
  it('i want mockReset', () => {
    fetch.req.mockReset();
    console.log('did not mockReset.. T.T', fetch.req);
  });
});

fetch.js

exports.req = method => {
  return `request method ${method}`
}

exports.reqGet = () => {
  return this.req('GET');
}