如何将模拟对象注入到构造函数中？

npm install --save-dev jest babel-jest @babel/preset-env

// UserService.js
import UserRepository from './UserRepository';

class UserService {
  constructor(userRepository) {
    this.userRepository = userRepository;
  }

  getUser(id) {
    return this.userRepository.getUser(id);
  }
}

export default UserService;

// MockUserRepository.js
class MockUserRepository {
  getUser(id) {
    return { id, name: 'Mock User' };
  }
}

export default MockUserRepository;

// UserService.test.js
import UserService from './UserService';
import MockUserRepository from './MockUserRepository';

describe('UserService', () => {
  test('should get user', () => {
    const mockUserRepository = new MockUserRepository();
    const userService = new UserService(mockUserRepository);

    const user = userService.getUser(1);

    expect(user).toEqual({ id: 1, name: 'Mock User' });
  });
});