implementing Unit Testing a React Component that Uses Context API and useReducer Hook
I'm upgrading from an older version and I'm not sure how to approach I'm confused about I'm having trouble writing unit tests for a React component that utilizes the Context API and the `useReducer` hook... The component is supposed to display user information fetched from an API and update it based on user actions. However, when I run the tests, I get the following behavior: `TypeError: want to read properties of undefined (reading 'state')`. I've set up a mock context provider for the tests but it seems like I'm not passing the state correctly. Here’s a simplified version of my component: ```javascript import React, { useContext } from 'react'; import { UserContext } from './UserContext'; const UserProfile = () => { const { state, dispatch } = useContext(UserContext); const updateUser = () => { dispatch({ type: 'UPDATE_USER', payload: newUserData }); }; return ( <div> <h1>{state.user.name}</h1> <button onClick={updateUser}>Update User</button> </div> ); }; export default UserProfile; ``` And here’s how I’m trying to test it: ```javascript import { render, fireEvent } from '@testing-library/react'; import UserProfile from './UserProfile'; import { UserContext } from './UserContext'; const mockDispatch = jest.fn(); const mockState = { user: { name: 'John Doe' } }; const mockContextValue = { state: mockState, dispatch: mockDispatch }; test('renders user name and updates on button click', () => { const { getByText } = render( <UserContext.Provider value={mockContextValue}> <UserProfile /> </UserContext.Provider> ); expect(getByText('John Doe')).toBeInTheDocument(); fireEvent.click(getByText('Update User')); expect(mockDispatch).toHaveBeenCalledWith({ type: 'UPDATE_USER', payload: newUserData }); }); ``` Despite creating the mock context, it seems like `state` is still `undefined` in the component when the test runs. I've double-checked that the provider wraps the component correctly. I'm using React 17 and Jest 27. Any insights on what might be going wrong or how to properly mock the context for testing? I'm open to any suggestions. For reference, this is a production web app. My development environment is Ubuntu 20.04. Could this be a known issue? I'd really appreciate any guidance on this.