用Jest在nestjs中模拟可注入模型

Question

我想对我的服务进行单元测试。在我的服务中，我有一个构造函数，它是：

ContractService.ts

  export class ContractService {
  private logger = new Logger('ContractService');
  constructor(
    @InjectModel(Contract)
    private contractModel: typeof Contract,
  ) {}

  async getContracts(query: PaginationInterface): Promise<FetchContract> {
    const { limit, page, skip } = paginationParseParams(query);
    const { sortBy, direction } = sortParseParams(query, ColumnDetails);
    const { count, rows } = await this.contractModel.findAndCountAll({
      where: {},
      offset: skip,
      limit: limit,
      order: [[sortBy, direction]],
    });
    const pages = Math.ceil(count / limit);
    const meta = {
      limit,
      skip,
      page,
      count,
      pages,
      sortBy,
      direction,
    };
    return { meta, data: rows };
  }
}

我的模型看起来是这样的：（模型是来自sequelize-typescript的类）

export class Contract extends Model<Contract> {
   .... 
} 

所以我想用JEST创建我的单元测试。当我试图模仿contractModel时，它找不到方法，即使我试图模仿它。

const mockContractModel = () => ({
  findAndCountAll: jest.fn(),
});

describe('ContractService', () => {
  let contractService: ContractService;
  let contractModel: Contract;

  beforeEach(async () => {
    const module: TestingModule = await Test.createTestingModule({
      providers: [
        ContractService,
        {
          provide: Contract,
          useFactory: mockContractModel,
        },
      ],
    }).compile();

    contractService = module.get<ContractService>(ContractService);
    contractModel = module.get<Contract>(Contract);
  });

  it('should be defined', () => {
    expect(contractService).toBeDefined();
  });

  describe('Get contracts', () => {
    it('Should return all the contracts', async () => {
      expect(contractModel.findAndCountAll).not.toHaveBeenCalled();
      await contractService.getContracts(defaultPagination);
      expect(contractModel.findAndCountAll).toHaveBeenCalled();
    });
  });
}); 

我在想，怎样才是嘲弄这个合同模型的正确方法。

Answer 1

而不是使用

{
  provide: Contract,
  useFactory: mockContractModel
}

你应该用

js prettyprint-override"> {
  provide: getModelToken(Contract),
  useFactory: mockContractModel
}

其中GetModelToken是从@nestjs/mongoose导入的。这将为Nest获取正确的DI令牌，以了解您在嘲笑什么。有关更多示例，请查看此git repo