NestJS跨包测试StockModule时GraphQLModule依赖注入失败问题

问题背景 #

我有两个独立的NestJS包，各自拥有package.json：

• 第一个是stock包，其中的StockModule导入了配置ApolloFederationDriver的GraphQLModule
• 第二个是test包，依赖配置和stock包完全一致，尝试用Jest测试StockModule功能时，导入StockModule创建应用上下文，Nest抛出依赖解析错误，提示找不到HttpAdapterHost。已确认所有@nestjs/*版本一致，甚至直接复制stock包的node_modules/@nestjs到test包，问题依然存在。

Stock包依赖配置 #

{
  "name": "stock",
  "dependencies": {
    "@apollo/federation": "^0.37.1",
    "@apollo/subgraph": "^2.1.3",
    "@nestjs/apollo": "^10.0.9",
    "@nestjs/axios": "^1.0.0",
    "@nestjs/common": "^8.4.7",
    "@nestjs/core": "^8.4.4",
    "@nestjs/graphql": "^10.0.22",
    "@nestjs/platform-express": "^8.4.4",
    "apollo-server-core": "^3.10.2",
    "apollo-server-express": "^3.10.2"
  }
}

StockModule代码 #

@Module({
  imports: [
    GraphQLModule.forRoot<ApolloFederationDriverConfig>({
      driver: ApolloFederationDriver,
      typePaths: [join(__dirname, '..', 'src', 'schema.gql')],
      playground: false,
      plugins: [ApolloServerPluginLandingPageLocalDefault()],
    }),
  ],
})
export class StockModule { }

TestModule测试代码 #

import { NestFactory } from '@nestjs/core';
import { StockModule } from 'stock';
import { Module } from '@nestjs/common';

@Module({
  imports: [StockModule],
})
class TestModule { }

describe('Stock Module ', () => {
  beforeAll(async () => {
    const app = await NestFactory.createApplicationContext(TestModule);
  });
 });

错误信息 #

[Nest] 7278  - 12/02/2022, 11:00:56 AM   ERROR [ExceptionHandler] Nest can't resolve dependencies of the GraphQLModule (?, GqlModuleOptions, AbstractGraphQLDriver, GraphQLTypesLoader). Please make sure that the argument HttpAdapterHost at index [0] is available in the GraphQLModule context.

Potential solutions:
- If HttpAdapterHost is a provider, is it part of the current GraphQLModule?
- If HttpAdapterHost is exported from a separate @Module, is that module imported within GraphQLModule?
  @Module({
    imports: [ /* the Module containing HttpAdapterHost */ ]
  })

解决方案 #

问题核心是createApplicationContext创建的是无HTTP适配器的纯应用上下文，而ApolloFederationDriver依赖HttpAdapterHost（由HTTP适配器提供），导致依赖缺失。以下两种方法可解决：

方法1：创建完整HTTP应用实例 #

改用NestFactory.create创建带HTTP适配器的完整应用，HttpAdapterHost会被自动注入：

describe('Stock Module ', () => {
  let app: INestApplication;

  beforeAll(async () => {
    app = await NestFactory.create(TestModule);
    await app.init();
  });

  afterAll(async () => {
    await app.close();
  });
 });

方法2：手动注入模拟的HttpAdapterHost #

如果不想启动完整HTTP服务器，可在测试模块中手动提供HttpAdapterHost的模拟实现：

import { HttpAdapterHost } from '@nestjs/core';

@Module({
  imports: [StockModule],
  providers: [
    {
      provide: HttpAdapterHost,
      useValue: {
        httpAdapter: { getHttpServer: jest.fn() } // 模拟必要方法
      }
    }
  ],
})
class TestModule { }

内容的提问来源于stack exchange，提问作者Ohdev