Vitest allows you to automatically mock entire modules or specific functions, making it easier to isolate and test code without manually creating mocks for every function. Auto-mocking is particularly useful when you are testing complex systems with many dependencies.

You can automatically mock a module using vi.mock():

vi.mock('./api', () => ({
  getConcertDetails: vi
    .fn()
    .mockResolvedValue({ band: 'Green Day', venue: 'Madison Square Garden' }),
}));

This will mock the entire api module and replace getConcertDetails with a mock function that returns predefined data. Auto-mocking simplifies the process of managing mocks in large tests by allowing you to define mocks upfront.