Jest Testing with Mocks

1const fetchUser = require('./fetchUser');
2const axios = require('axios');
3 
4jest.mock('axios');
5 
6describe('fetchUser', () => {
7  it('fetches user data successfully', async () => {
8    const mockUser = { id: 1, name: 'John' };
9    axios.get.mockResolvedValue({ data: mockUser });
10 
11    const result = await fetchUser(1);
12 
13    expect(axios.get).toHaveBeenCalledWith('/api/users/1');
14    expect(result).toEqual(mockUser);
15  });
16 
17  it('handles errors gracefully', async () => {
18    axios.get.mockRejectedValue(new Error('Network Error'));
19 
20    await expect(fetchUser(1)).rejects.toThrow('Network Error');
21  });
22});