Is it possible to mock responses during a detox end-to-end test

I'm currently making a react-native mobile application. I try to test my login button and fields and want to test the logic of moving to the account screen upon login.

Currently I got this as my testcase:

import {clickAccountButton} from "./Navigation";
//API
import nock from "nock";
import {API_URL} from "@env";
import {axiosPost} from "../app/config/api";

jest.useFakeTimers();

describe('LoginScreen tests', function () {
  beforeAll(async () => {
    await device.launchApp();
  });

  it('should show the login screen', async () => {
    await clickAccountButton();
    await expect(element(by.id('loginScreen'))).toBeVisible();
  });

  it('should have the header', async () => {
    await expect(element(by.id('header'))).toBeVisible();
  });

  it('should contain email and password form field', async () => {
    await expect(element(by.id('email'))).toBeVisible();
    await expect(element(by.id('password'))).toBeVisible();
  });

  it('should contain the login and forgotten password buttons', async () => {
    await expect(element(by.id('loginSubmit'))).toBeVisible();
    await expect(element(by.id('forgotPassword'))).toBeVisible();
  });

  it('should navigate to ForgotPassword onPress', async () => {
    await element(by.id('forgotPassword')).tap();
    await expect(element(by.id('forgotPasswordScreen'))).toBeVisible();
    //Click the account button again to return to the login screen
    await clickAccountButton();
  });

  it('should login successfully', async () => {
    //Give the following response to the next httpRequest
    nock(`${API_URL}`)
        .post('/api/v1/auth/login')
        .reply(200, {
          loggedIn: true,
          user: {
            id: 1,
          }
        }).persist();

    await element(by.id('email')).replaceText('hello@email.com');
    await element(by.id('password')).replaceText('foobar');
    await element(by.id('loginSubmit')).tap();
    

    //Double check: Check if the view with testID 'welcomeScreen' is showing
    //and the input field with testID 'email' is gone
    await expect(element(by.id('accountScreen'))).toBeVisible();
    await expect(element(by.id('email'))).not.toBeVisible();
  });
});

I expect the 'should login successfully' case to succeed because i'm intercepting the request and nock sends a response. This is not the case though. Instead it just does the actual request to my local API server which I don't want to use. Cause I don't want actual login details in my test.

Does anyone know how to handle this? Thanks in advance!

Jest and the app under test run in separate processes so normal Jest mocking techniques such as Nock won't work. Have a look at the mocking guide for Detox.

If you have a module such as apiClient.js in your app then you can mock that with something like apiClient.mock.js.