在 NestJS 中使用 Mongoose 测试服务

Question

我正在尝试在 NestJS 中测试我的 LoggingService，虽然我看不到测试有任何问题，但我得到的错误是 Error: Cannot spy the save property because it is not a function; undefined given instead

正在测试的函数（为简洁起见进行了删减）：

@Injectable()
export class LoggingService {
  constructor(
    @InjectModel(LOGGING_AUTH_MODEL) private readonly loggingAuthModel: Model<IOpenApiAuthLogDocument>,
    @InjectModel(LOGGING_EVENT_MODEL) private readonly loggingEventModel: Model<IOpenApiEventLogDocument>,
  ) {
  }
  
  async authLogging(req: Request, requestId: unknown, apiKey: string, statusCode: number, internalMsg: string) {
    
    const authLog: IOpenApiAuthLog = {
///
    }
    
    await new this.loggingAuthModel(authLog).save();
  }
}

这几乎是我的第一个 NestJS 测试，据我所知，这是测试它的正确方法，考虑到最后的错误似乎是正确的。

describe('LoggingService', () => {
  let service: LoggingService;
  let mockLoggingAuthModel: IOpenApiAuthLogDocument;
  let request;
  
  beforeEach(async () => {
    request = new JestRequest();
    
    const module: TestingModule = await Test.createTestingModule({
      providers: [
        LoggingService,
        {
          provide: getModelToken(LOGGING_AUTH_MODEL),
          useValue: MockLoggingAuthModel,
        },
        {
          provide: getModelToken(LOGGING_EVENT_MODEL),
          useValue: MockLoggingEventModel,
        },
      ],
    }).compile();
    
    service = module.get(LoggingService);
    mockLoggingAuthModel = module.get(getModelToken(LOGGING_AUTH_MODEL));
  });
  
  it('should be defined', () => {
    expect(service).toBeDefined();
  });
  
  it('authLogging', async () => {
    const reqId = 'mock-request-id';
    const mockApiKey = 'mock-api-key';
    const mockStatusCode = 200;
    const mockInternalMessage = 'mock-message';
    
    await service.authLogging(request, reqId, mockApiKey, mockStatusCode, mockInternalMessage);
    
    const authSpy = jest.spyOn(mockLoggingAuthModel, 'save');
    expect(authSpy).toBeCalled();
  });
});

模拟模型：

class MockLoggingAuthModel {
  constructor() {
  }
  
  public async save(): Promise<void> {
  }
}

Answer 1

问题是因为您将 class 传递给 TestingModule，同时告诉它它是一个值。

使用 useClass 创建 TestingModule:

beforeEach(async () => {
  request = new JestRequest();
  
  const module: TestingModule = await Test.createTestingModule({
    providers: [
      LoggingService,
      {
        provide: getModelToken(LOGGING_AUTH_MODEL),
        // Use useClass
        useClass: mockLoggingAuthModel,
      },
      {
        provide: getModelToken(LOGGING_EVENT_MODEL),
        // Use useClass
        useClass: MockLoggingEventModel,
      },
    ],
  }).compile();
  
  service = module.get(LoggingService);
  mockLoggingAuthModel = module.get(getModelToken(LOGGING_AUTH_MODEL));
});

Answer 2

经过更多谷歌搜索后，我设法找到了这个测试示例 Repo：https://github.com/jmcdo29/testing-nestjs，其中包括 Mongo 上的示例，还建议使用 this.model(data) 会使测试复杂化，而应该使用`this.model.create(数据).

进行更改后，测试按预期进行。

在 NestJS 中使用 Mongoose 测试服务

Testing Service with Mongoose in NestJS

javascript

unit-testing

nestjs

nestjs-testing