javascript - How to mock axios.create([config]) function to return its instance methods instead of overriding them with mock?

Question

I'm trying to mock axios.create() because I'm using its instance across the app and obviously need all of its implementation which is destroyed by the mock, thus cannot get the result of the get, post method properly.

This is how the code looks like in the actual file:

 export const axiosInstance = axios.create({
        headers: {
           ...headers
        },
        transformRequest: [
            function (data, headers) {
                return data;
            },
        ],
    });
    const response = await axiosInstance.get(endpoint);

And here is the mock setup for axios inside the test file

   jest.mock('axios', () => {
        return {
            create: jest.fn(),
            get: jest.fn(() => Promise.resolve()),
        };
    }
);

How could I get all of the instance methods in the axiosInstance variable instead of just having a mock function which does nothing?

Documentation for axios.create and instance methods: https://github.com/axios/axios#instance-methods

Answer 1

You can use jest's genMockFromModule. It will generate jest.fn() for each of the modules's methods and you'll be able to use .mockReturnThis() on create to return the same instance.

example:

./src/__mocks__/axios.js

const axios = jest.genMockFromModule('axios');

axios.create.mockReturnThis();

export default axios;

working example

---

Edit:

from Jest 26.0.0+ it's renamed to jest.createMockFromModule