Writing Integration Tests

What testing pattern is demonstrated in this integration test?

describe('User Registration', () => {
  beforeAll(async () => {
    await database.connect();
    await clearTestData();
  });

  afterAll(async () => {
    await database.disconnect();
  });

  test('should create user and send welcome email', async () => {
    const user = await registerUser({
      email: 'test@example.com',
      password: 'password123'
    });
    
    const dbUser = await database.users.findOne({ email: user.email });
    expect(dbUser).toBeDefined();
    expect(emailService.sentEmails).toContainEqual(
      expect.objectContaining({ to: user.email })
    );
  });
});

Unit testing with mocks
End-to-end testing of the full stack
Component isolation testing
Integration testing with external dependencies
This demonstrates integration testing with external dependencies: 1) Sets up and tears down a test database connection, 2) Tests multiple system components together (user registration, database, email service), 3) Verifies the complete workflow of user registration, 4) Checks both data persistence and side effects (email sending), 5) Uses beforeAll/afterAll for proper test environment setup and cleanup, 6) Tests actual interactions between components rather than mocks, 7) Ensures different parts of the system work together correctly, 8) Represents a real-world usage scenario.

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