use jest mock to run async function in isolation

Question

async await jest mock http request in node.jest

I can write my test like so
it('works with async/await', async () => {
  expect.assertions(1);
  const data = await user.getUserName(4);
  expect(data).toEqual('Mark');
});

but getUserName will be executed and it hit my backend and database, how to mock the function so that my test can be run in isolation?

Answer 1

You need to actually mock the user object. I don't have full context but you probably have something like const User = require('../user.js') . So with jest you can mock this by doing

jest.mock('../user.js')

jest.mock accepts also a callback where you can add there your own implementation but I prefer having a seperate mocks folder where you can keep your own implementation of the mock as it might make the tests a bit more cluttered.

You can check how it's used here where you call jest.mock and then the mock implementation .