将TypeORM存储库注入NestJS服务以进行模拟数据测试 [英] Inject TypeORM repository into NestJS service for mock data testing

问题描述

在此问题中，对此进行了长时间的讨论.

There's a longish discussion about how to do this in this issue.

我已经尝试了许多建议的解决方案，但是运气不高.

I've experimented with a number of the proposed solutions but I'm not having much luck.

任何人都可以提供一个具体示例，说明如何使用注入的存储库和模拟数据来测试服务吗?

Could anyone provide a concrete example of how to test a service with an injected repository and mock data?

推荐答案

假设我们有一个非常简单的服务，该服务通过id查找用户实体:

Let's assume we have a very simple service that finds a user entity by id:

export class UserService {
  constructor(@InjectRepository(UserEntity) private userRepository: Repository<UserEntity>) {
  }

  async findUser(userId: string): Promise<UserEntity> {
    return this.userRepository.findOne(userId);
  }
}

然后，您可以使用以下模拟工厂模拟UserRepository(根据需要添加更多方法):

Then you can mock the UserRepository with the following mock factory (add more methods as needed):

// @ts-ignore
export const repositoryMockFactory: () => MockType<Repository<any>> = jest.fn(() => ({
  findOne: jest.fn(entity => entity),
  // ...
}));

使用工厂可确保每次测试都使用新的模拟.

Using a factory ensures that a new mock is used for every test.

describe('UserService', () => {
  let service: UserService;
  let repositoryMock: MockType<Repository<UserEntity>>;

  beforeEach(async () => {
    const module: TestingModule = await Test.createTestingModule({
      providers: [
        UserService,
        // Provide your mock instead of the actual repository
        { provide: getRepositoryToken(UserEntity), useFactory: repositoryMockFactory },
      ],
    }).compile();
    service = module.get<UserService>(UserService);
    repositoryMock = module.get(getRepositoryToken(UserEntity));
  });

  it('should find a user', async () => {
    const user = {name: 'Alni', id: '123'};
    // Now you can control the return value of your mock's methods
    repositoryMock.findOne.mockReturnValue(user);
    expect(service.findUser(user.id)).toEqual(user);
    // And make assertions on how often and with what params your mock's methods are called
    expect(repositoryMock.findOne).toHaveBeenCalledWith(user.id);
  });
});

出于类型安全性和舒适性的考虑，您可以对模拟使用以下类型(远非完美，当在接下来的主要版本中开玩笑本身开始使用Typescript时，可能会有更好的解决方案):

For type safety and comfort you can use the following typing for your mocks (far from perfect, there might be a better solution when jest itself starts using typescript in the upcoming major releases):

export type MockType<T> = {
  [P in keyof T]: jest.Mock<{}>;
};

这篇关于将TypeORM存储库注入NestJS服务以进行模拟数据测试的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！