Difficulty with React Testing Library rendering custom hooks in unit tests
This might be a silly question, but I'm following best practices but I'm working on a personal project and I tried several approaches but none seem to work... I'm working with scenarios when trying to test a custom hook using React Testing Library. The hook in question is designed to fetch data from an API and return the loading state and the data once it's fetched. However, when I attempt to render the hook in my test, I'm getting an behavior stating `TypeError: want to read properties of undefined (reading 'data')`. Here's the code for my hook: ```javascript import { useEffect, useState } from 'react'; const useFetchData = (url) => { const [data, setData] = useState(null); const [loading, setLoading] = useState(true); useEffect(() => { const fetchData = async () => { const response = await fetch(url); const result = await response.json(); setData(result); setLoading(false); }; fetchData(); }, [url]); return { data, loading }; }; export default useFetchData; ``` In my test file, I have the following code: ```javascript import { renderHook } from '@testing-library/react-hooks'; import useFetchData from './useFetchData'; describe('useFetchData', () => { it('should return loading as true initially and data after fetching', async () => { const { result, waitForNextUpdate } = renderHook(() => useFetchData('https://api.example.com/data')); expect(result.current.loading).toBe(true); await waitForNextUpdate(); expect(result.current.loading).toBe(false); expect(result.current.data).toBeDefined(); }); }); ``` I've also mocked the fetch call using `jest.spyOn(global, 'fetch').mockImplementation(...)`, but it doesn't seem to affect the outcome. I've tried debugging with console logs in my hook to see if the data is being fetched correctly, and it looks like it is, but for some reason, the test doesn't recognize the state change. Am I missing something in the way I'm using `renderHook`, or is there something else that I should be doing to properly test this custom hook? Any insights would be greatly appreciated! What am I doing wrong? My development environment is Windows. Thanks in advance! My development environment is CentOS. I've been using Javascript for about a year now.