# Jest

> Jest configuration, mocking strategies, snapshot testing, and coverage.

- Skill: `a5c-ai/jest` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add a5c-ai/jest`
- Raw SKILL.md: https://api.skillmd.com/api/skills/a5c-ai/jest/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: a5c-ai (https://skillmd.com/u/a5c-ai)
- Updated: 2026-08-19
- Page: https://skillmd.com/skills/a5c-ai/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

```typescript
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