Jest

Jest Skill

Expert assistance for testing with Jest.

Capabilities

• Configure Jest for various frameworks
• Implement mocking strategies
• Write snapshot tests
• Configure coverage
• Handle async testing

Test Patterns

describe('UserService', () => {
  let service: UserService;
  let mockRepository: jest.Mocked<UserRepository>;

  beforeEach(() => {
    mockRepository = {
      findAll: jest.fn(),
      findById: jest.fn(),
      create: jest.fn(),
    };
    service = new UserService(mockRepository);
  });

  it('should return all users', async () => {
    mockRepository.findAll.mockResolvedValue([{ id: '1', name: 'John' }]);

    const result = await service.findAll();

    expect(result).toHaveLength(1);
    expect(mockRepository.findAll).toHaveBeenCalled();
  });
});

Target Processes

• unit-testing
• integration-testing
• tdd-development