If you have a service or module that you need to mock for tests, you can easily do this with Jest.

Mocking a Service

In order to mock one of your own services, to set it up, you can do the following in your test file:

import serviceToBeMocked from "./path/to/service";

...

jest.mock("./path/to/service", () => ({
    functionToBeMocked: jest.fn()
}));

From there, you can mock the implementation where you need it, for example:

describe("renders", () => {
    
    ...
    
    serviceToBeMocked.functionToBeMocked.mockImplementation(() => {
        return yourMockData;
    })
    
    ...
});

Mocking a Module

If you need to mock a module used in your application, you can also use Jest for this. If you needed to mock Axios for example, you can do the following:

...

import axios from "axios";

jest.mock("axios");

axios.mockImplementationOnce(() => 
    Promise.resolve({
        data: {
            id: 1,
            name: "Joe Soap",
            ...
        }
    })
);

...

When it comes time to make your assertions, can do the following:

it("does something", async () => {
    
    ...

    await wait(() => {
        expect(axios).toHaveBeenCalledTimes(1);
    });

    ...

});