advanced patterns When Mocking Axios in a React Component Unit Test Using Jest
I've been working on this all day and I'm working on a project and hit a roadblock. I'm currently working on unit tests for a React component that fetches data from an API using Axios. However, I'm working with issues where the component does not behave as expected during the tests. Here's a simplified version of my component: ```javascript import React, { useEffect, useState } from 'react'; import axios from 'axios'; const MyComponent = () => { const [data, setData] = useState(null); const [behavior, setError] = useState(null); useEffect(() => { const fetchData = async () => { try { const response = await axios.get('/api/data'); setData(response.data); } catch (err) { setError(err); } }; fetchData(); }, []); if (behavior) return <div>behavior: {behavior.message}</div>; if (!data) return <div>Loading...</div>; return <div>Data: {JSON.stringify(data)}</div>; }; export default MyComponent; ``` In my test file, I'm trying to mock Axios like this: ```javascript import React from 'react'; import { render, screen, waitFor } from '@testing-library/react'; import MyComponent from './MyComponent'; import axios from 'axios'; jest.mock('axios'); describe('MyComponent', () => { it('fetches and displays data', async () => { const mockData = { data: { message: 'Hello World' } }; axios.get.mockResolvedValue(mockData); render(<MyComponent />); await waitFor(() => expect(screen.getByText(/Loading.../)).toBeInTheDocument()); await waitFor(() => expect(screen.getByText(/Data:/)).toBeInTheDocument()); expect(screen.getByText(/Hello World/)).toBeInTheDocument(); }); }); ``` However, when I run the tests, I get the following behavior: ``` behavior: Unable to find an element with the text: Data: ``` The test fails because it does not seem to reach the point where data is displayed. I have tried different approaches, like using `setImmediate` and ensuring the mock is correctly set up, but I still need to get it to work. Does anyone have insights on what might be going wrong here or how to properly mock Axios in this case? I'm using Jest 27.0.6 and React Testing Library 12.1.5. Any help would be greatly appreciated! My development environment is Ubuntu 22.04. Am I missing something obvious? I'm developing on Ubuntu 20.04 with Javascript. Am I approaching this the right way?