nestjs 單元測試 createTestingModule 依賴注入

Question

我希望你能幫助我。 我正在使用帶有最新 angular/nestjs 的 Nx（日期：2 月 26 日）

    ...
    "@nestjs/common": "^7.0.0",
    "@nestjs/config": "^0.6.3",
    "@nestjs/core": "^7.0.0",
    "@nestjs/platform-express": "^7.0.0",
    "@nestjs/platform-socket.io": "^7.6.7",
    "@nestjs/websockets": "^7.6.7",
    "jest": "26.2.2",
    "@nrwl/jest": "11.4.0",
    ...

我無法使用帶有 Jest 的 NestJS 運行單元測試我想測試以下服務：

@Injectable()
export class CoreApiService {
  logger = new Logger('CoreApiService');
  apiEndpoint;

  constructor(private httpService: HttpService, configService: ConfigService) {
    this.apiEndpoint = configService.get('API_SERVICE_ENDPOINT');
  }
}

我收到以下錯誤：

TypeError: Cannot read property 'get' of undefined

所以似乎 ConfigService（以及 httpService）總是未定義的。

當記錄 httpService 和 ConfigService 時，它總是未定義的。 即使我嘗試實例化new CoreApiService(new HttpService(), new ConfigService())類的新實例，我什至嘗試過new CoreApiService({} as any, {get: (...params} => {return 'foo'})在測試本身

它將始終是上述相同的錯誤。

測試文件：

import { Test, TestingModule } from '@nestjs/testing';
import { CoreApiService } from './core-api.service';
import { ConfigModule, ConfigService } from '@nestjs/config';
import { HttpModule } from '@nestjs/common';


class ConfigServiceMock {
  get(key: string): string {
    switch (key) {
      case 'API_SERVICE_ENDPOINT':
        return '';
    }
  }
}

describe('CoreApiService', () => {
  let module: TestingModule;
  let service: CoreApiService;

  beforeEach(async () => {
    module = await Test.createTestingModule({
      imports: [HttpModule, ConfigModule],
      providers: [
        CoreApiService,
        { provide: ConfigService, useClass: ConfigServiceMock },
      ],
    }).compile();
    service = module.get<CoreApiService>(CoreApiService);
  });

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

我什至嘗試過： .overrideProvider(ConfigService).useClass(ConfigServiceMock)

先感謝您！

編輯 03/01

似乎模塊本身的編譯步驟失敗了......所以對於當前的測試文件，日志“COMPILED”將永遠不會被執行。

 CoreApiService › should be defined

    TypeError: Cannot read property 'get' of undefined

      22 |
      23 |   constructor(private httpService: HttpService, configService: ConfigService) {
    > 24 |     this.apiEndpoint = configService.get('API_SERVICE_ENDPOINT');
         |                                      ^
      25 |   }
      26 |
      27 |   private static createRequestConfig(options: RequestHeader): RequestConfig {

      at new CoreApiService (src/app/core-api/core-api.service.ts:24:38)
      at Injector.instantiateClass (../../node_modules/@nestjs/core/injector/injector.js:286:19)
      at callback (../../node_modules/@nestjs/core/injector/injector.js:42:41)
      at Injector.resolveConstructorParams (../../node_modules/@nestjs/core/injector/injector.js:114:24)
      at Injector.loadInstance (../../node_modules/@nestjs/core/injector/injector.js:46:9)
      at Injector.loadProvider (../../node_modules/@nestjs/core/injector/injector.js:68:9)
          at async Promise.all (index 5)
      at InstanceLoader.createInstancesOfProviders (../../node_modules/@nestjs/core/injector/instance-loader.js:43:9)
      at ../../node_modules/@nestjs/core/injector/instance-loader.js:28:13
          at async Promise.all (index 1)
      at InstanceLoader.createInstances (../../node_modules/@nestjs/core/injector/instance-loader.js:27:9)
      at InstanceLoader.createInstancesOfDependencies (../../node_modules/@nestjs/core/injector/instance-loader.js:17:9)
      at TestingModuleBuilder.compile (../../node_modules/@nestjs/testing/testing-module.builder.js:43:9)

  ● CoreApiService › should be defined

    expect(received).toBeDefined()

    Received: undefined

      44 |   it('should be defined', () => {
      45 |     console.log('SHOULD BE DEFINED')
    > 46 |     expect(service).toBeDefined();
         |                     ^
      47 |   });
      48 | });
      49 |

      at Object.<anonymous> (src/app/core-api/core-api.service.spec.ts:46:21)

當前的測試文件如下所示：

import { Test, TestingModule } from '@nestjs/testing';
import { CoreApiService } from './core-api.service';
import { ConfigService } from '@nestjs/config';
import { HttpService, INestApplication } from '@nestjs/common';

class ConfigServiceMock {
  get(key: string): string {
    switch (key) {
      case 'API_SERVICE_ENDPOINT':
        return '';
    }
  }
}

class HttpServiceMock {
  get(): any {

  }
}

describe('CoreApiService', () => {
  let module: TestingModule;
  let service: CoreApiService;
  let app: INestApplication;

  beforeEach(async () => {
    console.log('beforeEach')
    module = await Test.createTestingModule({
      imports: [],
      providers: [
        { provide: ConfigService, useClass: ConfigServiceMock },
        { provide: HttpService, useClass: HttpServiceMock },
        CoreApiService,
      ],
    })
      .compile();
    console.log('COMPILED');
    app = module.createNestApplication();
    await app.init();
    service = module.get<CoreApiService>(CoreApiService);
  });

  it('should be defined', () => {
    console.log('SHOULD BE DEFINED')
    expect(service).toBeDefined();
  });
});

我也玩過提供者部分的順序，但我想這不相關......

Answer 1

您可能想嘗試兩件事：

1. 初始化您的 Nest 應用程序。 在beforeEach中，在模塊中調用compile()之后，添加以下行：

app = module.createNestApplication();
await app.init();

2. 不要在您的測試中導入ConfigModule 。 這將初始化實際的配置服務，您不需要它，因為您是 mocking 它。