Writing Unit Tests with Jest

What testing technique is being used here?

jest.mock('./database');

test('fetches user data', async () => {
  const mockUser = { id: 1, name: 'Test' };
  database.getUser.mockResolvedValue(mockUser);
  
  const user = await fetchUserData(1);
  expect(user).toEqual(mockUser);
});

Integration testing
End-to-end testing
Mocking dependencies
This demonstrates dependency mocking: 1) Isolates code under test from external dependencies, 2) Provides controlled test environment, 3) Enables testing without actual database, 4) Allows simulating different scenarios, 5) Improves test speed and reliability, 6) Prevents external factors affecting tests, 7) Common practice for testing data access layers, 8) Essential for unit testing external integrations.
Performance testing

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